If they still make Kindle cables like they used to, you may suffer from sub-optimal charging. Looking at some specs, 28 AWG only carries 1.4A for chassis wiring. 28AWG is normally when a cable starts feeling oddly thin and flexible. But it seems unlikely to me that the cable could endanger your light. microUSB is a particular spec, so a reputable company like Amazon should definitely be making cables to spec. There was some excitement recently about a Google engineer buying all the usb c cables on amazon, testing them, and writing a bunch of reviews about the ones that weren't made to spec, but those were third party international sorts of sellers.