Is it normal to be irritable

Me and my boyfriend have been together for almost three years. And for that I can say that I'm comfortable, secured and inlove with him. Its been a year and a month since i started working for a certain company. Sometimes i feel so stressed upon working for a graveyard shift and then shifting schedules that really racked my head out. When we hang out or see each other after hours of my duty he used to throw jokes on me. And I dunno but it really irritates me and makes me frown and mad.. is it normal to feel that way coz everytime we see each other especially when he's joking on me i'm so irritable and losing my mood? Any comments or advice will be appreciated. thanks