First of all, I am not a parent, but I am a teacher. It is hard to say without actually knowing your kid, but I will say that it seems a lot of times labels are put on kids too quickly when they are simply just being a kid.
I would definitely listen to what they have to say about what they are seeing in your son at school, but I would think twice before letting them label him as anything, unless it (1) interfers with his learning or (2) interfers with the learning of others. If it doesn't, then they cannot say anything other maybe he's a little odd!
I have worked with a lot of kids, and I can tell you that some kids are just *weird*! They are still normal kids though when it comes to most things. Honestly, this may blow your head up even bigger about your son, but a lot of the behaviors you described (being glued to things he is interested in, obsessed with certain topics, adult talk, etc.) are indicative of gifted kids, and some gifted kids can be a little "strange"! (But in a good way!)