I think the "obsessive" interests can show up anywhere, especially when you are talking about kids. Autism is on a spectrum and I'm sure in the "mild" area are "tendencies" which bleed into other diagnoses and problems/non-problems. Look at bipolar individuals during mania, for example, they often can stay up, multiple days in a row working on a "project" that has caught them. People with obsessive compulsive disorder can have collections similar to a person with asperger's, interests.

What do you think would change, if you had this diagnosis rather than another?