Originally Posted by cny-bikeman

Unlikely it has anything to do with the pedals themselves. See below.

The pedal (or crank arm) tightness is much more likely the issue. It is more rare that the BB or pedal is the problem, and because sound and feel travel it's also not always possible to tell which side is the problem. The bike should be returned to the shop and everything in the BB area should be checked for tightness, then the bike should be ridden under high pedal pressure to check before returning it to you. Only if the standard tightening procedures don't work should one look further.

Too often the BB or pedal is jumped to as the cause, which can result in unnecessary expense. If one puts on a new BB or set of pedals and the problem goes away it could have simply been that the replacement was properly tightened.