Not a "problem" per se, my first Ruger was a brand-new P-85 in 1987 that, of course, came under the recall. That was a very smooth process; I think they paid for return shipping, sent me a box, and when they returned it sent a new mag to compensate me for my shipping it to them. Their CS was great even back then. No issues with before or after, just complied with the recall request. I ended up trading that P-85 in on a KP-89DC in the early '90's. I still have that one. Won't ever part with it, either.
The only other problem I've had was the medallion falling out of the bottom of the grip on the stock of my 2014 10/22 TD a couple years ago. I called Ruger hoping I could get a replacement medallion and they sent me a complete stock instead! I posted a thread on here at the time, but I still can't get over how great their CS is.