Sexual behavior in altered male ferret

Question
I have a 6 month old male Marshall ferret who is altered. I got him from a pet store 2 months ago and he was already altered. Yesterday I introduced him to a new altered female ferret who is close in age and size to him.  He proceeded to mount her and bite her neck.  He is a little aggressive in play with the other animals in the house, so that is normal for him, and he isn't hurting her but I'm concerned that this behavior is sexual and not just a dominance behavior.  I've been reading that this is a sign of adrenal disease, but I thought he was too young for that.  I am a college student and I cannot afford unnecessary vet visits and tests. he saw a vet a couple weeks ago who said he looks healthy and he doesn't have any other problems.  Is there any chance that this behavior is normal?

Answer
It is certainly a little young to be Adrenal Disease, but I would keep an eye out for the signs just in case.  It sounds like completely normal adolescent male ferret!  Ferrets play very rough with each other, but can usually work it all out with each other.  Keep an eye on them, but it sounds fine and normal.