Pee feeling during fingering?

(A little T.M.I I think)

Okay so my boyfriend is a pleaser, when we're getting to it he'll go straight to giving me pleasure and he'll go to town...my legs shake and everything it will get so intense my body starts to pull away :/ but lately when he fingers me I get this feeling that I have to pee, and I thought maybe it was because I need to pee but I only get that feeling when his fingering me, like when I make him stop the feeling stops, and when he eats me out I don't get the feeling or when we're having sex I don't get that feeling either, so can someone please tell me why I get the feeling or if I'm not alone...

P.s he'll asks if I'm okay since I've been stopping him so soon and I tell him it's fine because yeah not sure I want to tell him...I know childish.