89 D150 LA318 Roller TBI /a999 2wd 1/2ton

So I got my engine rebuilt and I've only put 44 miles on it so far. I changed the oil and it was dark, not pitch black but it was time. Anyways I noticed it had fine brass colored metal in the oil and cut the filter open to see the brass specs. The only thing I can think of that is brass is the bearing for the dist intermediate shaft. So I pulled the dist and shaft to take a look at the bearing. It has some wear on it for sure. I'm not sure if this is normal. Do they wear into each other and eventually stop giving off metal? Or did the machine shop mess something up? Any thoughts? Things I could check? Thanks.