Hopefully this will become canon in Season 5 or even Rainbow Rocks.
When Sunset Shimmer is going for her tour, one of the girls remembers her friends and says "You're friends with Rainbow Dash? The girl who had a crush on Soarin' this whole year and last year?"
In Rainbow Dash's episode, when she will sing her entire solo song, maybe Soarin' could fly near her and say "Wow Dash! I knew you were a natural at flying, but I never could have imagined that you could sing so well!"