Lukemac, I think the answer to your question is "we can't tell from here based on this information." If you're concerned, which I understand that you are, I think you should seek an evaluation.
Yes, that kind of obsessive categorizing is a hallmark feature of AS, as is the resistance to being separated from the obsession.
AS kids can sometimes be reasonably flexible about the things they don't care about, but deeply inflexible about their obsessions.
Attempts to limit "music time" are met with "I'M mad at you. I am so so so so angry. Why are you being mean to me" and so on, along with crying.
That could be a classic 5yo temper tantrum, or classic AS inflexibility. It takes a professional to sort this out.
How are your DS's social skills? Pretend play? Unscripted cooperative play? Does he care about and understand how others are feeling? Is he an anxious person? Those would all be markers that would likely help you start to sort this out.
DeeDee
