My Gelding Urinates ALOT, what do you think it may be?

I have a 5 year old Arabian, he pees ALOT. He is very healthy, living on a pure alfalfa pasture. He drinks alot of water, so I thought it may just be because hes well hydrated. On our most recent trail ride, which was 3 1/2hrs, he urinated a total of 7 times. And each time was at least 30 seconds in duration. He fully up-to date on Worming and shots, and super healthy. Should I be worrying? Or get it checked out? Our other 8 year old Arabian hardly pees at all. We are lucky if he urinates once on a trail. . . o_o