Okay, this happened to me last December coming home.
I bought a small bottle of Asbach along with some other things and the cashier placed it in a plastic bag and sealed it.
So then I went through security and they weren't going to let me take it with me. (something about the volume of it?).
So why sell stuff in Duty-Free if you can't take it on the plane?
They DID let me take it, but the lady acted like she was doing me a favor.....
B~