I have this new phal with some spots on the underside of the leaves. It came from Trader Joes and was outside on a display in the parking garage with almost no sun. It was rather dry also, so I don't suspect rot or sun damage.
It doesn't look threatening to me, but i wanted to double check. Should it stay or should it go?
It should be fine... pull it out a bit and take a quick peek at the roots. If they look fine, I think those spots are probably just Phal teenage acne.
I know that was a tacky answer, but hey, it's late, what can I say????