I'm getting a "Can't use flash because phone is overheating" prompt on iPhone 5 camera screen??

After a slightly rigorous late-night photography session at an underground concert, my camera app gave me a pop-up prompt saying that it cannot use flash because, either the phone has overheated, or the LED flash has overheated... i can't remember the exact words, and i havent been able to replicate it since. But it was continuous for about 20 minutes, and the flash wouldn't work.

Has anyone had this pop up? Im guessing it's a known quantity judging from the very exact nature of the language in the prompt. I've used the camera much more heavily, a few nights ago, with lots of flash, compared to yesterday but this is the first time it has said this.

EDIT: It happened again, but this time there was some serious downloading just prior to it.

EDIT 2: Nevermind. Just read the Anandtech review [Thanks JillyBeanWasNotMyGirl :)]. Anandtech says it's new, but sort of normal. Carry on folks! Though i'd still like to hear from other's who have encountered this, and if they have any tips on how to avoid this?