I wanted to transfer a fde g23 and they told me that since they were a Glock dealer, they weren't allowed to transfer in Glocks from other sellers. They said Glock would cancel their contract if they found out.
I said that was the first I've ever heard of anything like that and other shops didn't seem to have a problem with it... I just transferred it elsewhere.
Perhaps the other places I've been weren't official Glock dealers?