Yes, I get this issue sometimes, often after long stints on hotspot using lots of data (which actually seems like a 'normal' behavior, if you ask me)... that's a lot to ask for from a smartphone... I'd be curious to see if anyone doesn't get reboots after using several gigabytes worth of data...
I turn hotspot on/off frequently and it usually doesn't reboot. I get about 1 reboot every other day or so, and thats with fairly high use of the phone.
now if you are only using hotspot briefly, and not doing much else on the phone, and still getting reboots, I might worry about that. But that's just my 02.