[jrochkind1]

> No, it's not. Licenses do not restrict rights of the copyright holder, ever.

Sure they can. You can definitely give someone an exclusive license, typically for a set period of time. You have agreed by contract not to license to anyone else, even though you are still the copyright holder. A license is simply a kind of contract, and you can contractually agree to whatever you want -- unless restricted by law otherwise, and there are certainly restrictions on legal contracts, but exclusive licenses are not at all unusual and entirely legal. Presumably you were compensated adequately for giving up (usually temporarily) the ability to license to anyone else.

Of course, open source styles of licenses including CC, are never exclusive, because this sort of license is offered to the public at large. When you CC-license, or GPL-license, or apache-license your work, you're are offering the work to the public at large under that license, that's what those kinds of licenses are for.

But traditional licenses are usually offered to a particular party, and they certainly can be exclusive.