Texture of his semen

I have just started seeing a guy who lives away (he's in the Air Force) and we've been lucky enough to get together a few times this month. Every time we have sex his semen is quite watery at first with some really lumpy bits and there's usually a lot of it! Anyway I'm not inexperienced and have seen my share of semen but this is not something I'm used to. Not that it bothers me I'm just wondering if this is normal?
He was in a long term relationship before me but still went ahead and got tested before we stopped using condoms. He has mentioned that he doesn't masturbate regularly due to usually working long shifts   and the fact that he prefers sex but I'm not sure that a couple of weeks build up would do this? 
I haven't mentioned it to him but just wondering if anyone has any clues/experience of this?