Just strip the paint already. Don't worry about the PC yet; worst case is you need to wash the frame after stripping. You need to find out what's going on. I see those bumps that looked kind of like distortion are brass. It's unlikely IMO that those are just slop. Too much brass there. More likely the tops of the seatstays cracked or came loose, and the brass blobs are a sloppy brazed repair.