Mine, too - but they're battery powered, right? Direct current means no fluctuations, no flicker.
Actually, some (if not all) LED flashlights cycle the LED very quickly for their reduced power settings... I learned this while peeing by flashlight during a power outage. The strobing is too fast to perceive but it turned my urine stream into globules.
5D Mk III, Elan 7e, Nikon J1, some old rangefinders
Tamron 24-70 2.8 VC, 70-200 f/2.8L IS II, 400mm f/2.8L II, Sigma 85mm, 50mm, & 35mm f/1.4's, Rokinon 14mm f/2.8, Canon 2x Extender II, Kenko 1.4x, 430 EX II, Elinchroms