Along with all other devices utilizing lithium batteries? My cell phone has gotten uncomfortably hot a few times. In fact it gave new meaning to the term "hot pockets"! However in my experience, turning it OFF reverses the temperature trend. As for the vape devices, some are engineered and built better than others. As well, some users are known to modify the heating coils on their devices to increase heat and therefore vapor output. This increases current demand on the battery, making it more vulnerable to overheating.
Whatever the case, there well may be some calls to ban vape devices on airplanes even though that may open a big can of worms with respect to all lithium battery equipped devices. The vape industry may have shot themselves in the foot when they promoted all those awful "flavors" that leave one yearning for the smell of ordinary tobacco smoke. I don't care whether they ban them or not, but people who don't like them will use this to get rid of them while they get to keep their entertainment devices.