Hi,
Congrats on your new Milgauss.
To respond to your question, no; 31 hours of non-wearing time is not enough for that to happen. A milgauss should have a power reserve of 48 hours, as it's a rep; that'll probably be a bit less, but not 17 hours less than that. Perhaps you haven't winded it correctly, or not at all. Just wearing it, might not be enough (to start with); you should wind the crown a little. 30-40 full spins will be enough, then wear it properly.
Once winded and worn, it'll perhaps get you somewhere near 48 hours. You won't have to wind it all the time if you wear it, but you'll have to wind it (in order to not-lose time) after you haven't worn it for awhile.
If your watch was not fully wound to start with wearing only 3-4 hour a day would hardly top its power reserve.They need at least 8-10 hours wearing each day to keep power reserve topped up.On a full manual wind when watch is at peak power reserve it should run between 40 to 48 hours while off wrist. If you're wearing it for 4 hours of sitting at a desk and typing, it's unlikely to put enough power into the spring to keep the watch running (my Daytona just stopped on me, yesterday, while I was wearing it!). If you're out jogging for those 4 hours, with arms pumping, you'd be good to go. Give it a good wind (40 turns, clockwise as you look at the stem) and you should be fine.
Good luck!