As Amy said, the cervix is very sensitive in early pregnancy and can bleed very easily. Most pregnancy books and doctors even advise patients that they can bleed a little after intercourse due to the cervix.
If it doen't happen again, and there is no cramping, I would forget about it and move on. I know that's hard, as I had a m/c at 9 weeks last year, and I'm just 8 weeks now. So, I'm right there with you guys.
Oh, and tell her to wear her glasses into the bathroom. LOL