I am so glad this thread has popped up, I have suspected this in my dh for ages.
He will drone on and on about one very minor topic, for instance someone is talking about rush hour traffic and dh will pick up on one particular road/street and talk non stop about that road and how the traffic was/is/will be, and he cannot be moved onto another topic.
He will not make eye contact with people he talks to, be they neighbours, salesman in car-garage, the dc's teachers at parents evening etc.
He is very blunt and will say what is on him mind (without sugarcoating it) which leads to arguments with his (very sensitive) sister.
He is obsessed with 'ordering' things, from biggest to smallest, in alphabetical order, in order of colour.
He has OCD tendencies wrt routines, for instance he works as an engineer and insists certain processes are followed to the letter, even if they don't need to be.
He has an over-active gag reflex, be it brushing his teeth, dental check-up or even the slightest bit of skin on a sausage or chewy bit of veg.
All in all though, these could not be signs of anything at all, I had not really thought about it until a year ago....
But when all is said and done, he is my dh and I love him!