Oh my, yes, it took me ages to find out what was causing these random reboots...
In my case it is not completely random, it only happens say between 7 PM and 6 AM. It must be linked with the times f.lux kicks in and tunes the color temperature.
Before understanding that it was f.lux, I posted on xda to get help to understand the log lines.
Please see the linked post for more detail, but basically I can invariably correlate the following log line
with the reboot times (which I track with Bootlog Uptime).
I don't remember if I had this issue with OOS 3 as well, but it's certainly still there with OOS 4.0.3.
I cannot reproduce the reboots by playing with the settings (e.g. by running the different color presets examples).
Crashes happen on v22 I believe, unless v22 was released in the last two days.