I have a diagnosis of Asperger's. Repetative behaviours is one of the triad of impairments. There are lots of symptoms of autism that vary from person to person but all autistic people share the triad of impairments. If you don't have one of them, you don't have autism.
That said, repetative behaviours is a very broad brush. The primary form of repetative behaviours in Asperger's is what are called 'special interests'. For my daughter that means she is obsessed with and spends all her time on anything to do with Anne Frank, the holocaust, Africa and Japan. For me, it's certain authors, where I have all their books and read them again and again and again. For my husband (3 AS in the house) it's his radio, he's a complete electronics geek.
The second area that repetative behaviours covers is routines, rituals and lists. We go on holiday to the same place every year, have done so for 30 years. We get there, put up the tent, go and get fish and chips which have to be eaten out of the paper sat on the bench overlooking the beach, followed by bubblegum ice-cream. Any deviation from this and the holiday is ruined. It is our ritual and it has to be followed. Do things have to be done in a special order, does not following that order cause problems. Does he makes lists. Does he (like me) have lists of lists). It all about creating systems and systems within systems to create a sense of order out of a chaotic world.
If you still think your husband needs a referral for assessment approach the GP again but go better prepared. They are looking for the triad of impairments. Go through each one and the behaviours associated with it and make a list (easy for an aspie 
) of all the problems he has in this area. Show the GP how he meets the diagnostic criteria for each of the triad.
There is a book called Parenting Your Asperger's Child which you may find useful. I know it's not you child you need help with, but that book has a long and detailed checklist in it of autistic behaviours that come under each of the triad and how they look with examples of what that means. One of the triad is impairment in communication, what exactly does that look like? It's also very useful because it brings up things you may not have even connected to being autistic. For example talking to loudly or quietly, sitting or walking too close to you, deconstructing their food. I had it because of my daughter but I used it to help me work out what I needed to tell the doctor for my own diagnosis too.
Oh yeah and don't forget the 4th unofficial triad: WoW subscription :o