dont feel too bad. accidents happen, just be more careful next time.
observe your baby today, and if you think she needs to go to the vet, then definitely take her tmw. (or today if it gets worse)
it's a tough call, but personally i usually just take my furkids to the vet just to be sure, because they can't talk to us, and i dont' feel like i can be sure that they are ok, unless the vet tells me they are ok...plus, i always ask the vet a bunch of questions while i am there, so it's like getting a mini course
do what makes you feel comfortable, i tend to be more cautious, therefore, i've had the vet ask me. "why did you bring him in?" (because he couldn't see anything wrong with my rabbit) (even though the rabbit was limping at home, but was walking fine at the vet's office) so i just told the vet that he was limping at home, and i wanted to be sure that he is ok.
maybe you can put a bell on your baby, so you can know where she is at all times so you won't accidently step on her again.