Last week I put some new self-closing hinges on a cabinet door. The
old hinges had lost their self-closing ability.

The new hinges did not exactly match the size of the old ones. The
part of the hinge that attached to the cabinet door was a bit shorter
than the corresponding piece on the old hinge. So I had to make new
holes in the cabinet door to screw the hinges on. Otherwise,
everything was fine, and the door again closed by itself.

Then today, something in a hinge / the hinges / the door itself (not
sure which) has started to make a loud noise, kind of a pop or a very
short squeak, when I close the cabinet door.

I've tried loosening and tightening all the screws on both of the
hinges, but the squeaking persists.

What has happened, and how do I track down and eliminate the source of
the noise?