Was on a Alaska flight from SEA to SNA yesterday morning and the flight crew did mention the 7's and to keep them turned off at all times, no charging.
That said, I'm not too worried about open flames in a small space on an airliner (see below.) It wasn't that long ago we had smoking-sections and before that, non-smoking sections. (And before that, what the hell are you talking about?)
One note though. I work for a company that makes the cabins for airliners and there is a whole lot of Flammability testing on EVERYTHING. That sticker that says where the flotation device is, reams of paperwork and a page for each individual sticker. I don't think I can name anything that is more tested than an modern airliner. Truly a marvel of engineering. An overhead luggage compartment, designed to be very light, I can pick one up with one arm, will take a static load of over 2 tons just so nothing will come flying out when there's a hard landing.
Interesting side note, we did have one factory blow up (collapsed the roof) when the machine impregnating the non-flammability into cloth didn't get vented correctly.