I think the whole issue is really how the balls are stored. If the Penn Championships are stored at room temperature at the store and by the player, they are fine. Unfortunately, I think they are left outside for months at these larger chain stores until they are ready to be brought inside for sale.
Do you really have any idea how they are stored? I think purely conjecture - unless you moonlight at Wally World instead of hustling home to the wife - like you say.
On my way to OTC to play DA