Could be a speech impediment, or maybe he just has an unusual way of speaking. Some people with autism have speech issues, but that alone doesn't indicate autism.
There isn't really a polite way to ask someone if they have a condition, especially if you hardly know the person. If he doesn't have a disorder, he'll probably be embarrassed. If he does have a disorder, asking him could make him uncomfortable; he might not want to lie about it but not want to tell you, either. Asking other people about it is disrespectful because it's his business. He should get to choose whether or not to disclose a diagnosis, if he has one.
Since nothing he's doing seems to affect you, my advice is to just let it go.