OK experts, any ideas on a strange effect in this shot, taken with my A200 & Tamron 70-300?

(Large size to get the detail of the issue to stand out.)

Note on the trombone players' face, collar, and shoulder to some extent, the radial dark, shadow like lines that weren't really there.

They don't extend across the trombone, don't extend to the white glove, or onto the silver trim on the hat.

They seem to be some short of reflective effect from some point toward the right side of the shot. Can this all be off the curvature of the back end of the trombone? I've never seen anything quite like this, and obviously didn't recreate it.