I very much doubt that this occured.
The flap and gear leaver on the 737 are in completely different places, look completely different and move in different directions. The action of reaching forward to raise the gear, shortly after "positive climb" is called, is a very strong motor-programme; it is unimaginable that someone would reach down down to the centre pedstal instead and try and move the flap leaver.
Incidentally, there is a detent at the flap 1 position (for single engine go-arounds) and therefore it is impossible to raise the flaps from 5 to up in one smooth action.
Cheers,
RBG.