flap problem

[Frank Benvin]

I took off with 1/3 flaps and heard the flap motor cut in in my hedd set several times. I watched the indicator and flaps and they were going up and down ever so slighty by them selfs but not enough to make a drastic pitch change. I tried 2/3 flaps, same problem. At full flap no problems. My mechanic checked the system and could not find a problem.
Any suggestion????