Maul wasn't known for being patient - quite the opposite. He often got irritated, even for serious reasons. No one seemed to want to be near him, in fact most people ran away and avoided him if they could.

He was on a mission, it was classified to not say anything about it and his senses told him that someone was following him..It was irritating. Because he didn't know if someone was following him and wanting to hurt him or was just intrigued. Either way, it irritated him immensely. Because this person followed him practically everywhere and was always behind him. On top of that, they we're trying to be secret..for Force's Sake he was a darkside user, of course he will feel it!

So once, he stopped walking and said;

“What do you want?! I literally can feel that you're following me.”