Yep. I've been having the same problem with my new P345. Noticed it before I fired it. I may have jimmied it somehow by releasing the slide while not having a magazine installed?? It seems to occur incrementally every time it decocks. I talked to Ruger before firing 20 rounds thru it. The pivot pin still is working itself out. There are a few posts on the (ahem) other forum. I'll probably be sending mine back to Ruger for repair.
It's not normal. Call them.