A litlle bit of urine came out of my boyfriends ?

I was drinking all night with him and he tinkled some while I was giving him a hand job. I didn't take notice until after but I realized his urinary bladder looked like it was ready to burst (he looked like a balloon where the bladder is). I let him go and hee peed for about 2 minutes straight. Even so, I thought a guy couldn't leak urine when he is horny?