I'm pissed, but should I be?

My " boyfriend", or this guy that I'm seeing is really starting to piss me off! He's about 10 yrs older than me, but the age difference doesn't bother us. We have already had our own discussions about that and we're fine with it. So we can be texting ( we usually text throughout the day and FaceTime at night) and he will randomly stop answering for hours, without saying anything. Not even letting me know that he's busy or he'll text me later or whatever. This has happened 2 or 3 times but for example today, the last text he answered was at 8 am and it's almost 7pm right now... I sent him 3 other text throughout these 10-11 hrs but other than that I'm just not going to txt him again and I'm gonna wait. Should I be pissed? Or at least annoyed? Because I am. Should I talk to him about it? Or do the same thing to him?or do I need to calm down and relax?