Bbay putting things in diaper?

My baby woke up at 3am last night for a diaper change. I had been working and my husband was watching her. So I panicked when I went to change her diaper and there was a learning card in it, like the color/shape learning cards! I have never ever seen her do anything with her diaper besides wear it. So I can't picture her just being able to put something in it without her dad noticing her doing it. When I asked him about it he got defensive saying well he didn't know how it gotnin there that he didn't put it in there. I said well if she did, he should have been watching her enough to notice. Especially since she is into EVSDYTHING now. Idk what to think. I really can't picture her doing it herself, but also don't think je would just put a card in there?