This happened to me a couple times at BWI. I largely let it ago as the people were trying to be nice for once. Not much different than the guy that gives smiley stickers to the kids. He couldn't read it anyway. I took it off the first chance I could.
I've educated my son in other ways what a travesty TSA is. He even yelled "Kip Hawley is an Idiot" at the checkpoint.