Hi there!
At that age, I would just keep going with the flow and keep watching his cues to let you know if he is hungry or not. You are still getting to know each other and it may take several more weeks for a consistent routine to fall in to place. If he is breastfed, I think 3.5 hours is too long for a 5 week old to go. IMO, 2-3 hours is more appropriate for that age. Even if he's a bigger baby, he's still young and your supply is probably still being established. If he's bottlefed, then you will know he is snacking based on how much he takes at each feed.
Also, not every baby snacks because their mom's milk supply is low. That can be a cause, but it can also just be a habit that pops up. Both my boys were snackers at one point or another, and I never had issues with my supply.
HTH!!