Warning: Spoiler! (Click to show)
Rey previously had made a comment to BB8 when trying to send it on its way regarding such phenomena on Jakku
This. And also, how he fought pretty well against Ren Kylo, but got his ass whupped by a random storm trooper.
I think that the Rey character was pretty well done. Her great first time piloting of the Falcon, which was better than Han's in Empire Strikes back, was a bit of a wtf moment.
I think that it's much less Rey being a Mary Sue than it is Ren Kylo being so lame. His retort to Rey saying that Han was like the father she never had. "You would have been disappointed." Sigh. Go tell your therapist, emo Vader.