Anyone have an idea why my TPMS light would start to flash exactly one hour (to the minute) after starting the vehicle and driving it? It will stay on proportionally to the whole length of the drive - so if driving for 3 hours, will continue flashing for 24 hours, if driving for 4 hours, 36 hours until the flashing stops.

I have aftermarket sensors from discount, including the spare. The spare is an aluminum stem, while the others are rubber. All are new within last 2 5 years and testing shows battery is good in all 5 sensors.

At Discount now and they are replacing the aluminum with a rubber so all are the same. See if that helps but still curious why the warning light would come on exactly one hour after start.

Write-up: How to Disable (Bypass) the TPMS

I'd have them re-upload the sensor IDs to the ECU.
Discount tire uses Dill sensors, I have not had any issues, being almost two years on a set.

Our family fleet has all the TPMS sensors operating properly, I send my kid out with our TPMS scanner to check psi, not needing to take a valve cap off, or fiddle with the spare.