It takes them about 48 hours to digest meals. It seems like mine are a bit lazy for a little bit even after digestion, so I think 3-4 days sound about the right amount of time for them to be coming out of their food coma.
The snake is most likely cruising its viv looking for another meal. It also could be exercising after resting for awhile. It's healthier to wait a bit longer than 3 -4 days to feed your snake though. If you have a baby feed it every 5 days, an adult can be fed once a week. If it's gaining too much weight with that much food, once every week and a half is acceptable.
In the wild, snakes are opportunistic feeders. If they happen upon a mouse nest or something in the wild they stuff themselves. This is because they may not get another chance at a meal for awhile. We definitely keep our snake better fed than they would be in the wild. I'm not really sure about the laying in ambush vs. sneaking up on prey. I would guess they move around to where the food is, because they are a pretty active snake.
It's nice that you see your snake out and about. Snakes are crepuscular, meaning that they are most active at dusk and at dawn. It seems to me that they feel more comfortable in low lighting. This is probably why you see your snake at night.
If you're worried about following a feeding plan that emulates what the snake would experience in the wild, don't worry about that too much. As I mentioned above, our snakes are pretty pampered compared to wild snakes. Even if your snake wants a second mouse after his/her meal or is begging for food 3 days after its last feed, don't give in!! Feeding too often is known as "power feeding", and it can seriously shorten the life span of your snake. It's not good for their little bodies to always be digesting.
One last thing to say.. it's probably good that you wait until your snake is hungry and activly looking for food again before disturbing it. If you take your snake out too soon, even if the regurge factor is not an issue, you could get pooped on! Snakes usually poop the first time they are active after a big meal. Sounds like TMI, but if you get pooped on you'll realize it's actually a handy thing to be aware of.