In the story, the main character is flashing back to how he acquired a very rare Gibson Les Paul when he was 15-16. He bought it from a rather low individual for what is a dump price. The main finds it's a stolen instrument and returns it to the owner, who is a late age black r&b guitarist. I'm wondering if I'm risking a stereotype here.
I wouldn't worry too much, while it might fit into various stereotypes, I don't think actively avoiding these traits is necessary. In fact, it could be argued that to avoid it is still acknowledgement of the stereotype.
I wouldn't think it would matter if it is thought of as a stereotype of not. Actively avoiding the stereotype might make the story seem to Politically correct.
I've met more than one elderly, black blues musician. I don't think there is anything stereotypical about that, if that's what you're worried about.
If it's a stereotype, it's one of the nicer ones. But seriously, don't worry about it. You could even lampshade the whole thing if you wanted.