accent

The local garage replaced the timimg belts and accessory belts on my
Accent. One month later, I had to bring it in because there was a
squeaking sound under the hood. The mechanic simply tightened the
belts and all was well. Now another month later, the squeaking sound
is back but not as pronounced.

Is this a case that the belts are coming loose or do they stretch when
new and need re-tightening?