QH wrinkles his nose

My QH has Qrinkled his nose for the past 5 years, but I was wondering why? He did it yesterday when I was getting hatlers ready to be put on, and he wrinkled his nose for a bit and when his halter was on he stopped, I've seen other horses do this also.. is he mad or upset?

Is he doing this?

Isn't that just when they smell something interesting? I thought that stallions do that normally when they smell a mare in heat.
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No, its the side behind his nose. I couldnt find any pictures.

Good be your horse is smelling his halter

Its like before they sneeze but he never sneezes his lip stays down too.

I had his halter outside of their pen, wasnt close to them.

Hmm that sounds silly. I doubt its because he's mad or anything

Hes done it for the past few years and he's will be 14 next week, I was just wondering.

Is he pinching his nose behind his nostrils? So that spot wrinkles?