The music that plays after Rey fixes DO’s squeaky wheel is the same ominous cue as after she slices the rock on Ach-To.
I wonder what the connection is. The rock prefigured Luke’s death. Fixing the wheel… I’m not sure. Someone pointed out to me that BB8 charging DO is just like Ben healing Rey.
Honestly the music is probably coincidental.
Yeah, someone noted that Rey told BB-8 how healing works after healing the snake. I think she mentioned something along the lines of BB-8 not being able to do that, but then later he gives D-O some of his own energy, having learned it from Rey.