The same thing happened to me a while back. Friday I took my car back to the shop that installed the tires and asked them to see if the sensors were good. They tested them, and all 4 were sending out a signal. Next they connected a programmer to the OBD port. Then they carried the programmer to each wheel, starting at the front driver's side (clockwise) and programmed each sensor. Next they reconnected the device to the OBD port and the light went out. The light has been out now for 4 happy days.

I guess they didn't program it correctly the first time they tried, or didn't bother.