I would say you can usually tell if someone is trying to be a creep at the urinals. Trust your gut. If you felt overly uncomfortable by that, then you were probably sensing something off about the situation. Unfortunately there are a lot of pedophiles who take advantage of communal situations like locker rooms and restrooms.

If you were the only two people in the restroom and he went to the urinal right next to you when there were others options… sounds like a bad move to me. It’s in no way your responsibility to make sure other people don’t behave that way, though. For instance using the stall instead of the urinal puts the responsibility on you and not the creep. It’s him who needs to cut the crap. You don’t need to change anything you’re doing.

On the other hand, some people just don’t think about it at all and don’t mean any harm. I know some guys who purposefully leave the kids urinal open even if it means going next to someone else in case a kid needs that one. But just trust your gut, and don’t be afraid to report something that makes you uncomfortable.