Of grease and cranks
My Tempo was doing this when I first got it - then I read the manual. Try pedaling backwards every once in a while to smear the grease around and see if the problem goes away. I just got in the habit of giving the crank a couple of reverse turns as I pull up to the stop sign at the end of the block. It's plain ol' automotive grease, injected through a plain ol' zerk fitting.