Gustafson, who is romantically linked to LPGA Commissioner Ty Votaw, had a long birdie putt on the par-3 14th and went through her routine. She seemingly grounded her putter and noticed the ball was twitching so she backed off and after she did, the ball rolled down a ridge.
According to the rules, if a player grounds his or her club, the ball has been officially addressed and if it moves, that is a penalty stroke. The replays seemed to show Gustafson clearly over the ball with the putter head grounded, but officials declared the replays inconclusive and gave Gustafson the benefit of the doubt.
'From what I could tell, yes, the player's putter was behind the ball,' said LPGA Tour rules official Jim Haley. 'Through what Sophie told us, she was bound and determined to tell us she was especially aware that is a penalty situation, if she does ground her club.
'She told us she did not ground her club. Through that conversation, we determined that we weren't going to dispute her integrity and we determined there was no penalty in that situation.'
On the very next hole, Gustafson missed the green and stamped down a ball mark just off the edge of the green. That is also an infraction but officials determined the mark was not in her line, so no penalty.
'She did not improve her line of play on the 15th hole,' said Charlie Williams, another LPGA Tour rules official.
When it was all said and done, Gustafson fired an 8-under 64 to finish the tournament at 14-under-par 274. This was her fourth win on the LPGA Tour and her first since the 2001 Subaru Memorial of Naples.
'If it's a close call, I think you should look because you always want to remove the doubt,' said Gustafson, who pocketed $200,000 for the win. 'It has been two years since I won on the LPGA Tour, so it's really nice to be up here again.'
Beth Daniel and overnight co-leader Rachel Teske tied for second at 12-under- par 276. Daniel shot a 2-under 70 on Sunday while Teske, who bogeyed two of her last three holes, managed a 1-under 71.
Annika Sorenstam, the defending champion and new member of both the LPGA Tour and World Golf Halls of Fame, found water at the 17th and double bogeyed the hole. She shot a 2-under 70 and finished alone in fourth place at 11-under- par 277.
The final determination on the possible penalties was not made until after Gustafson completed her round. She was told not to sign her scorecard after the round and her and playing partner Juli Inkster brought their caddies to the television truck, where the replays were reviewed and the final decision was made.
The problem going on was that while the questions were being answered about the penalties, the three other players with chances of catching her were on the course, not knowing about Gustafson's situation.
'I had no idea until we walked off the green,' said Daniel. 'By the time I started making putts, it was kind of too late.'
'I saw they asked for a ruling, that's all I knew,' said Sorenstam. 'My caddie and I thought we had to birdie the last two and of course I was trying to play aggressive.'
The rules debate marred an otherwise spectacular round by Gustafson. She holed a bunker shot for eagle at the first, then birdied five of her next six holes to vault to the top of the leaderboard.
Gustafson made her first mistake of the round at the par-4 ninth. She chipped her third into a bunker and left with a double-bogey 6, in the process, dropping one shot behind Teske who had one birdie and eight pars on her front nine.
Gustafson rebounded with a four-foot birdie putt at the 10th to tie Teske for the lead. Gustafson drained a 20-footer for birdie at the 13th to take a brief lead but Teske rolled home a four-foot birdie putt at the 12th to once again tie for first.
Teske sank a 15-foot birdie putt at 13 while Gustafson was dealing with her problems at 14. After Gustafson made par at the hole, she holed a 12-foot birdie putt at 15 to match Teske.
Teske struggled down the stretch. She missed the green at 16 and made bogey when her four-foot par save skated by the right edge. Teske, a two-time winner this season, came up 10 feet short with her chip at the 17th and took another bogey, falling two behind Gustafson.
Se Ri Pak, who led after the first two rounds, carded a 1-over 73 on Sunday and took fifth place at minus-9, followed by Inkster, who shot a 70 to finish at 8-under-par 280.
Grace Park (69) and Cristie Kerr (70) shared seventh place at 7-under-par 281. Meg Mallon took ninth at minus-6, while Lorie Kane finished a shot behind Mallon at 5 under par.