I'm completely baffled by my house-trained dog's habit of urinating WHILE eating, HELP!?

I have 2 small dogs; a papillon and a 7 month old small (8lb) terrier mix. The terrier is incredibley smart, and he was a breeze to housetrain. He NEVER has accidents, and has been consistant with his house-trainging since he was 2 months old. He always lets me know when he needs to go out, and is able to go at least 6 hours home alone uncrated without accidents. So I just can't understand why when I feed him at night, the second he starts eating, he starts peeing! I immediately pick him up and put him outside, and wait for him to pee, but he won't! Then, after 10 minutes or so, I'll let him inside and let him eat, and he'll start peeing again! This can go back and forth (eat-pee-out-in-eat-pee-out-in) for what feels like forever, until he's "empty". I've never had a dog who's had this problem, has anybody seen this before? What can I do to prevent this? I was letting him out before he gets his dinner to prevent him peeing, but now he associates with going outside at a certain time of night with getting his dinner, and won't pee outside at that time :/