Texting

Jennifer
've been going out with my boyfriend for 8 months, I've always known he's awful at texting me back but he always has his phone on him! It's normally not a big deal but he's moving abroad and we're going to be long distance. Am I justified at getting annoyed that it takes him hours to reply? How do I bring it up without sounding clingy? Don't think we'll work if it carrys on!