*Crawls into traffic*
it's mostly harmless, done for fun and for the lulz. why do they do that at anime conventions? bc we know doing it out in the real world would be viewed as bizarre XD
but in all seriousness, the concept of the master/pet relationship is pretty interesting. sure, I call my significant otter my "little pet" but it doesn't mean we are in a master/pet relationship.
Pet has been used as a term of endearment for a while, so I'd consider that normal. And adorable.