The NICS system has been pushed past capacity several times over the last few weeks. The Saturday before Christmas, we couldn't get through at all. There was actually a recording directing dealers to call back later.
There were also some ~60 minute delays today. It's just a function of drastically increased traffic.
Oh, and guys, the NICS system is run by the FBI, not the ATF.
In the depth of winter I finally learned that there was in me an invincible summer.