I'm thinking Cervix. Your uterus is wayy up there and your cervix will move slightly. Also, depending where you're at in your cycle it can be closer to the opening of your vagina or further away at times. I don't think you have anything to worry about. Alot of women will check their cervix to see where they're at in their cycle, close to ovulation and such when they're trying to conceive. :)
Hi Rose, I think what you felt, was just your uterus, so your OK.
Good Luck