How much blood was there? Often, women have ovulation bleeding--right before, during, or after O. So, unless it's tons of blood, it's probably nothing. If it's more than a little blood, though, you might want to put a call in to a doc. I would get my periods every week and a half or so sometimes...and that's when I wasn't bleeding full-time! I do have mid-cycle spotting right before O sometimes, though, and it scared the crap out of me the first couple of times! I was so angry that AF was starting before I could even O.
I hope this is all it is--often, ovulation bleeding can be a sign of particularly "strong" O, which is a good thing!
Keep us updated!