given how many people have chimed in here and other threads and some on Apple Support message boards, I would say it is not
wise to swap out one's phone for this issue as you could likely get one with an issue that actually is more isolated and hardware-related instead.
Sort of reminds me of iPhone OS 4.0 on iPhone 4. The proximity sensor for making calls like gave up after no time, except I heard so many people with the issue I held off. Low and behold, 4.1 onward made my proximity sensor flawless, no longer face-dialing people while on the phone... I held off on swapping my phone because everything else worked great, and it was a good call in the end because I went to Europe with it and needed that preserved baseband to have ultrasn0w/be able to use my AT&T iPhone as a phone. Prepaid data goodness was a wonderful addition overseas.
Most evidence points to it being an iOS 6 bug. Especially since 4S users can reproduce a springboard crash by dragging an icon to a folder on another page
though I haven't had my hands on a 4S/iOS 6 device to test it out. Any major iOS x.0 version has a few screwy things out of the box, sometimes some of the flaws are more obvious than others.
As long as it weren't happening on like a daily basis or anything..
Reminds me, my 4S I got ended up randomly shutting itself off a few times over the course of the time I had it (like 6 months) i.e. would go to a movie, not turn my phone off, check it, and find it to be off and have to turn it back on again. Wasn't sure what the deal was with that, but everything else worked great except for it being hot and the screen being terrible quality relative to my 4, but I didn't want to swap it for fear of getting one with serious serious issues. The swap game isnt' a fun one.