Book 3-4 plot hole

>!So, in year 3 Rich Weaver is in Subtlety and Weapons. He doesn't make it to Subtlety in year 4. By default he went into Weapons, but I don't see that. Where'd he go? I mean he's still around because Dean Blaine can get "fresh samples" for the mimic to do her thing. Just some random thoughts in my relisten of the books.!<