This is an issue with me too. It happens at random times although it happens to me like once a day after the engine has warmed up and I am at a complete stop. I am in texas and right now the temps have been almost to 110 degrees.
I've been running with a P0456 engine code (it's not the gas cap) so I was thinking that it could be related since I have evap issues.
I do have an aftermarket intake. AFE. with RPI's
Although this is a concern, my biggest concern is passing inspection! lol