I've seen really really bad cases of scale rot leave long scars on the belly after it's been cleared up .... that would be my best "guess" without seeing the animal in person ... a bad thermal burn on the belly might also heal like that.

Regardless ... you should always QUARANTINE QUARANTINE QUARANTINE .... new animals from unknown or untrustworthy sources just aren't worth it unless you do!!!!

The other thought that I had was that it would be a shame if the scar was surgical ... removal or a cyst or perhaps worse could have left internal scar tissue that could make breeding impossible ... although, I feel that would be a long shot.

If she's a freebie ... and you QUARANTINE ... you really can't go wrong at 1500 grams.

-adam