New sound when flying?

My IRN's feathers were all neat and green however there now appears to be a grey one abruptly in the middle of them on his wing.

When he's been flying today it's been making a different sound.
The best way I could describe it is sounding a bit like a helicopter.

Is this anything to be worried about?

Edit: He also seems a little more violent than usual, could this just be molting?