Sticky fluid when urinating, Please help!?

This morning when my fiancee used the bathroom, he had a hard time starting to urinate, then a little bit of a sticky substance (it looks kinda like the lubricant pre ***) came out and he urinated fine, then after a lot came out, like half a shot gl amount. We have fairly regular , and he masturbates when we don't. We have been together for 7 years, monogamously. Could this be some kind of bladder or seminal problem, or just that he had a semi wet dream that didn't finish or something. He has never had this problem before.