iron headcovers are something else to worry about. I have X20 Tour irons with a brush-metal finish, so it would not do much good anyway.
One problem with iron HCs is getting moisture trapped inside, and starting rust you wouldn't get with normal air drying.
A local golf shop had a small-college golfer as a player's rep, and he talked about iron HCs. He put them on his irons before putting them in the equipment van or on the airplane, and took them off at the tournament site. Then, after play was over, he super-cleaned the irons, dried them, and put the covers back on for the trip home.
HE used them strictly for protection in transit.