When we moved into our house 2 of the 7 doors were damage and we could not find ones which matched. Solid core doors were way out of our price range, so we got all new hollow core doors, and I had them all professionally installed.
Right after the install we painted all of them. The worked great for months, now it seems they are starting to bow in the center, looking at the door from a top view you could see it bowig into a "u" shape
I called up the pro guy and he told me its either a material problem or a paint problem, which could be true.
What the deal? how do I fix these? All my new doors are crapping out at the same time!
If the warpage seems to have stabilized you could carefully remove the door stop and
reset it to the new door shape....Not ideal but functional. Doors, especially hollow core doors
can warp over time. As Ron said; paint them on all 6 sides.