About ten days ago I had a couple of used tires installed on the rear of my RL. I had thought my rear tires were in good shape until I pulled the tires to replace the rear brakes a few days earlier and saw steel belt showing on the inside edge of both rear tires. Guess it's time to have the rear alignment checked, but I knew since I was about to drive a couple thousand miles that I'd need some new tires pronto.

Since then, several times I'ver received a "Check TPMS System" message on the dash. It goes away after while and once again shows the pressure for each tire. Do I just need to retrain each sensor or is something else going on?