It seems odd to me... my dogs pee every couple hours normally. I mean they can hold it for a long time, but they do every time we go out. Maybe he is peeing while walking and you just don't notice? My boxer boy doesn't take the time to stop and pee, he just pees. lol My boy Sam has to stop and mark like 20 times (even when there is no pee left!) every time we go out.
I would ask your vet about it. I guess maybe it could be normal for certain dogs.