D.B.
Totally normal. It's entirely developmental and beyond his control.
If it's just occasional, then yes, you can try reducing liquid intake for a few hours before bed, and of course he should pee before bed. But it can be hard to tell if he is peeing just as he wakes up some 8-9 hours after going to sleep, or if he's doing it at 3 AM.
My son had a long history of this and wasn't dry on his own until around 11.5 - we actually used a medication called DDAVP based on the advice of the pediatrician and a pedi urologist -- otherwise our child would never have had a full night's sleep and couldn't go on sleepovers. I don't recommend the alarms - they are horrible to listen to, and they are counterproductive because they don't go off until the child is already wet.
If it's occasional, I'd wonder if he was having a dream or was in a half-wake/half-dream state and he actually thinks he got up and went to the bathroom. That happens once in a while.
If you don't want to use Good Nights or a similar product (he might balk at them or feel badly, although you can tell him he's going through a growth phase and it's temporary), you can at least minimize the disruption in the middle of the night (if that's when he's peeing). We put a fitted sheet down as usual, then put a waterproof pad down (we used his old crib pad - just flat, not fitted) and then put another fitted sheet on top. We kept a pack of wipes and an extra pair of pajamas by his bedside. If he woke up wet, we did a quick strip of child (wipes & new pjs) and a quick strip of the bed (top fitted sheet and pad removed, leaving a clean dry sheet ready to go. We left a plastic laundry basket right there for the wet stuff, and went back to sleep, dealing with it in the morning.
The think to do is keep this very low key, let him know it's very common (even if other kids aren't talking about it), and make sure there's no shame or annoyance about it. He's not a "baby" and it has nothing to do with "training" - it's not a learned skill, it's entirely physical, which he cannot control while asleep.