To find out if power comes back on tap into a hot leg on the line side of the main with an inline fuse and install an outlet. Plug in a radio when the power is out and crank it up. Sucks when the power comes back on at nite but at least you know. Again make sure you know how to do this correctly or ask for help
So you're hooking in before the main? Seems like that would be against code and maybe a little dangerous no? Great idea tough. It sounds like your power has kicked back on in the middle of the night haha.