Yes, we did discuss that the judges for these art contests have been "regular" people, not artists. DD actually does consistently get picked for art things where an art teacher chooses art to go on display regionally, etc. It's not that she has never been recognized, so she needs to keep that in mind. But she doesn't win the fun, splashy things.
Life does tend to come very easily to DS. I don't see him negatively affected by it thus far. However, it's something to keep in mind.
DS is quite unlikely to continue to win at art as he gets older, and that's fine with him, I think. It's so hard because he really doesn't care about this and DD does, so much. He just thinks it's fun to win. The other area where he recently won something big is important to him and something where he puts in serious time, so that's different.
Unfortunately the two also play the same sport (not my idea!!!), and DS is more naturally gifted.