I am glad you are noticing and care so much about your daughter... There may be another explanations - like listening to people talking about it, seeing something on TV or maybe watching animals - our cat does that kind of stuff with teddy bears, which is kind of disturbing, so you can hope it is not the worst case scenario...
However, I would recomend you to talk to your daughter about secrets, tell her you love her and that you will always love her and that she can trust you, that you are here for her. Have you noticed any other changes in her behaviour? If you are worried about certain person, try to ask her how she feels about this particular person... Ask her if she is afraid of someone, if she doesn´t like somebody...
Silence doesn´t mean it´s ok! Make sure she gives you an answer... Sometimes children don´t talk, when somebody asked me, I said "no" or didn´t say anything at all, which meant "yes" - but nobody noticed, everyone assumed it meant "no", no one really thought about the possibility I was abused, they just asked me during a conversation about another topic and I was too shocked and scared to say yes... It took me many years to be able to start talking. Just let her know she can tell you anything, that you are here for her.
I hope with all my heart it will be ok, but please, remember no matter what happened, you love your daughter and are supporting her, which is the most important thing. Wish you strength.
