seen this myself but I have heard of it happening with Ball Pythons. Someone we know had it happen with his adult female Ball Python last year and he saved it in a baggie, refrigerated it and brought it over to show us. I also remember someone posting pictures of something similar happening with one of their female Ball Pythons on the Ball Python forum a while ago.
I'm not sure exactly what it is but there was some discussion about it possibly being an aborted follicle or a blood clot. So apparently it does happen although I don't think it's common. I believe in both instances I know about with the Ball Pythons, the females were okay, there was just a weird clear/jelly mass with some blood in it.
I hope this helps. Glad to hear your female is all right though.
Thanks,
Celia
-----
Celia Chien
www.ExoticsByNature.com
2006 Boa Constrictor Morphs Calendar
2006 Ball Python Morphs Calendar