Camera flash disabled due to heat issue

I left my iPhone 4 charging for about 3 hours until it was fully charged. I went to take a picture and the camera flash switch had a warning symbol. When I clicked it, it stated that my flash was disabled due to excessive heat. I quit the camera app and reopened it and the flash was working fine afterwards.( note the phone did not feel hot whatsoever.) Should I be worried about this. There was no overheating warning on the lock screen just in the camera app.

Thanks.