Had Tires Balanced and Rotated - Next Day, A Flat Tire

Toyota recently put a new frame under my 2005 Tacoma. While driving, I noticed a small vibration in the steering wheel that wasn't there before the new frame. I took it to a local tire store and had them rotate the tires and also balance them. Sure enough, that solved the vibration problem, but the next day, the left front tire was completely flat. I removed the tire and checked for a nail, etc. but found nothing. I pumped it up and let it sit in my garage for 2 days, and it was still holding air. I remounted it on the truck and its still ok. I'm positive that it was not intentionally flattened by someone. Could adding a wheel weight possibly cause a leak but then reseal itself? This has me stumped.

 

My local tire guys forgot to add the gasket (part D) that seals on the rim and valve stem nut (part E). This gasket seals the valve stem (outside of rim) and the TPM sensor (inside of rim). When I went to add air, just looking at the valve stem wrong would cause air to leak by. I also found a couple valve stem nuts that were only finger-tight.

I'd check and make sure these gaskets (part D) are present, and also that the valve stem nuts (part E) are snug (but not too tight). I believe the spec is 17 in/lbs

 

My truck doesn't have the tire pressure moniters, but the valve stem is always a good culprit to look for when there's a slow leak. I pumped the tire up to 33 lbs yesterday and it has not lost any air yet. I still can't figure out how it went completely flat overnight the day after having this work done. My old aluminum wheels are off of my 2000 Tundra, which I sold for parts. I think when they balanced them and added the wheel weights, that could have caused the leak. Who knows? Thanks for the info on the TPMs.