Propane grill regulator freezing

So I got the tank refilled on my grill last night and hooked it back up. Used it today and when I went to turn it off noticed the regulator was covered in frost and when I closed the tank a burst of has shot out the relief valve or whatever on the regulator. Briefly scared me lol. Any thoughts on what would have caused this? I've never had this happen with this grill or any other for that matter.

 

Nothing to worry about; they probably overfilled the tank a little bit. The frosting occurs when liquid propane gets into the regulator and vaporizes to a gas there, rather than in the tank. It happens more often if it's humid out; there's more moisture in the air to accumulate on the regulator. The worst that'll happen is that it'll gum up the regulator and slow down the output to the burners for a couple minutes. If that happens, just shut the grill down and let it thaw out.
Once the level drops a little bit in the tank it shouldn't happen again, but if it keeps occurring maybe swap the tank rather than just refilling it. And if it's still happening, it may be time for a new regulator.