Sometimes Glock handguns will have small but sharp pieces of "flash" on the plastic parts from the molding process. If this happens on the trigger or trigger safety lever, the trigger finger will get abraded when firing as the weapon bounces during the recoil cycle. My lightly-used Glock 22 in .40 had this problem, and it was fairly annoying.
I very carefully scraped (with a small box cutter) and ever-so-lightly sanded (with fine sandpaper) the sharp edge of the tip of the trigger safety lever, and this took care of the problem.
Seems like this is fairly common on the newer Glocks; it was pretty rare 5-10 years ago.
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)