That "who knows how long" part is what would drive me crazy. I read a thing a while back about how even tiny runout on a wheel stand can mess with your balance job over time, like the tire reads fine one day and then slowly starts wearing weird. It's one of those things nobody checks until something feels off, and by then you've already done a bunch of tires on it. Did you notice it from a vibration or did you just happen to put a dial on it one day? Either way, at least now you know instead of guessing.