Goodness, T, I hope your mare isn't preggers! (Which one is it, Star or Destiny?) It could be a false pregnancy, I've heard of that happening with mares. You might check her dock and backend to see if they are getting mushy - if not, the issue is likely a false pregnancy. You should be OK unless the gelding in question was only recently cut before his, hrmm, association with your mare, or if he was a cryptochid and still had a testes left. Since your vet will be out soon have him check her over just to be safe. Fingers crossed that your mare is NOT with foal!