Any concerns using LED flashlight apps?

I've always wondered with flashlight apps, especially ones that use the LED light(s): Is there any risk of shortening the life of the LEDs? I noticed one app ("ASettings") gives a warning that doing so can "harm your phone"... which to me sounds even more ominous than burning out the bulb. I thought LEDs had a crazy long lifespan to begin with, so do I need to worry?