I just did SP101 trigger jobs for a couple of guys. Both of the guns were lousy with casting & machining flash inside. The trigger return piston bore was so rough I wondered if it had been bored on a screw machine. You may have a similar issue, if you're comfortable with the idea, I'd suggest breaking the gun down and cleaning and oiling the action. You could also send it back to Ruger, or pay a local Gunsmith yourself to do it if you don't want to mess with it.