thats not a dumb question, the answer = "no" your pet is not hidden when you hide.

now sometimes you will see your summoned pets ARE indeed sneak as u are and the nightblade shade as well but doesnt allways work fast enough.
but (normal) pets in general = no.


stealth is very serious. so this is important and pets should be in sneak with you but honestly, why u have a pet while sneaking? doesnt make sence.
entire class is all about stealth.