@Onespeedbiker, just checked the play in the cranks... doesn't seem to be any at all, but I can't check using the wall method because the bike's currently in the house. I'll take it to the LBS tomorrow and let him disassemble and clean the B/B and housing.

@Fietsbob, you are absolutely right; it's just that this started out the moment the bike dried up from heavy rains, so I'm figuring that crud/water might be the culprit, especially since the B/B hasn't done more than 500 miles since I last changed it.

I do have a spare new UN54 B/B, but will try and hold on to it, unless the existing UN26 really needs changing since the UN54 isn't readily available here in Greece.