Context: Two friends had a spar and one of them beats the other one. The following conversation then happens
「お前、ちょっとは手加減しろよ」
「俺とお前の腕に大した差はないよ」
「なんかムカつくな」
My question is to what is the cause of this emotion. Is it due to the way the speaker spoke as if they had little difference in skill (even though it was a relatively quick and easy win), is it just a general phrase to express annoyance at his loss with nothing specific in mind?