During play, punishment, greetings or physical contact some dogs might urinate and they also do tend to show submissive postures in interactions — for example, they flatten their ears against their head, they roll over and expose their belly or hold their tail low. (yorkiemag.com)
If this is the case, you might notice him displaying submissive postures during interactions. (pets.webmd.com)
When you're angry and upset, your puppy feels threatened by your tone of voice, body postures, and / or facial expressions, so he may hide or show submissive postures. (petallianceorlando.org)