no, because he's probably closing his eyes so he can hear his music better. I've done the same thing.
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My ideas for a good performance.

Have your act ready. You can start late, but not more than 15 minutes.

Be tuned. You can tune in the green room and touch up just a bit on stage.

Esp. for classical musicians - do not come out early and practice the tricky bits, all out of order and in different keys.

Dress nicely. This is an occasion. At least dress as nicely as the audience. Folk performers who look they are ready to go out and turn the compost are conveying disrespect for all.

Don't let anybody make a bunch of announcements at the start of the concert. The audience is on your side and eager for music - give it to them.

If anybody produces serious feedback, shoot them. (just kidding) There should be no feedback.

Be glad the audience is there, and let them know you are glad They could have stayed home.

Think about pacing and variety. Move from major to minor, from one timing (4/4, 6/8, 3/4) to another, from slow to fast, from instrumental to vocal.

(I once went to a bluegrass concert that was entirely in 4/4 time. What a bore.)

The first number should be a good one. Well=performed and exciting. You want the audience to think, "I'm glad I came!"

The last number of the first half needs to be really good. You want people to come back after intermission, not slip quietly out the door.

Somewhere in-between, slip in something peaceful or sad. People today are overstimulated and appreciate the chance to relaz.

I like an encore to be entirely different from what went before. It's dessert, if you will. If you've been playing Scottish music, play something Chinese (e.g.) for the encore.