i think you should mention it to day care, even if you say that you think it could just be stories, it cant hurt to tell them just so they can keep an eye out for it. your probably right to not say anything else to her unless she brings it up, you dont want her to think that its a good story to tell for fun IYKWIM!!
DD is the same, as soom as were in the house, its nappy of and if shes not fiddling, shes legs spread having a good look!!! DP always worries but i just have to remind him of the stories his mum used to tell abuot him pulling his penis so hard she thought hed pull it off!!!