Tire pressure sensors

As I was driving to my appointment this morning, the TPMS (tire pressure monitoring sensor) lit up on the dash.  Great.  Just as I was approaching the highway on-ramp, I get a low tire pressure light?  I got off at the next exit and stopped to check my tires.  Mind you, I check them before I even start the car and I didn't notice anything.  There was nothing wrong with the tires so I went on to my appointment.  I hate seeing the light on so I drove to the dealer after my appointment to get it checked out. 

This was the second time I had to take it in for inspection.  The first time was two weeks ago .. again, I was on my way to an appointment.  Geez .. there was no nail or anything wrong with the tires.  They re-programmed it and then gave me my keys back.

This time, they did the same thing .. however, the service guy told me that the next time this happens, they may have to replace the sensor itself since it's acting up and nothing seems to be wrong with the tires.  I used to think they were great to have but now .. they are beginning to annoy me.