Yet another TPMS ??'s

2009 Jetta, recent purchase. I noticed that the TPMS light was on and VCDS pulled up intermittent signal. Checking further, the sensors were basically dead battery status.

Ordered some OEM sensors (VDO correct part number) and had them installed.

Did the relearn procedure airing down to wake the sensor, let the car sit for a period of time and then drive. Comfirm with VCDS that the new ID's were listed and plenty of battery life for 5 years avg between the sensors.

Light goes out, all is well.

I took vacation and didn't drive the car for a week.

Headed back into work hop in the car, and 2 miles down the road, TPMS light blinks and shows again..
VCDS shows no comms to sensors..

Did VW really go this direction, where if the car sits for too long, it loses track of the sensors? (IDs are still correct). Do I need to do the relearn again? Something else going on? Where should I go from here?

If all else fails, I'll look into going with the ABS monitoring route, but given the car has the direct monitoring available I'd rather use it instead.

Update.

Had time tonight, aired down to re-wake sensors.

All but one reports to the car.

I guess I found the probelm.

Speaking of finding TPMS problems, I dropped a big one.

I was getting a TPMS light on my 2009 Jetta, and I could not use VCDS to remove the code (I love Ross Tech and VCDS, BTW.)

After reading some snippets from this forum, I went and checked my tires! And sure enough, I had mounted one tire without TPMS, a rubber stem. So I swapped an extra wheel with TPMS, and used VCDS to remove the code.