STS Tire was able to identify and fix an air-leaking TPMS sensor by using a sensor patch kit for $40 parts and labor. The kit itself was $13. Assuming it holds up over the long term, its way better than replacing a still functional (but air-leaking) TPMS sensor.

Just an fyi in case anyone runs across this issue.

 

Thanks for the info Jason. Whenever I have my tires changed, I have DT replace the seals in the TPMS. It usually costs about $5 per tire, IIRC.