IMHO if it were a slow leak, you'd have way less than 45 in there 10 days from your last pump (if your starting psi is around 80 as I'm assuming, for a hybrid and compared to your front tire). It might just be gradual air loss from not pumping it up for that 10-day period. I pump every day that I ride. I've lost up to 40 psi in a tire over a DAY, much less 10. If you really want to be hyper vigilant, I don't see why you wouldn't pump on a pre-ride basis.

K.