Husband made me sad :(

My husband and I text all the time while he is at work. Not every day but pretty much. I do NOT repeat text him if he hasn't responded, and if he doesn't respond at all that's totally fine, I understand that he's at work and doesn't have time. Well, I texted him today just about my day and how the kids are doing and IMMEDIATELY after I sent the text, I shit you not like 5 seconds after, he calls me freaking out! He said "please don't text me while I'm at work, I don't need the stress." He didn't even say hello or anything and it just took me by surprise so it kind of upset me. I said "okay I'm sorry I won't bother you any more" and I was a little teary eyed because it was so harsh, and then he gets PISSED. He was like "oh my god I knew it would turn into this" and just got all flustered with me. I am so beyond confused. What the he'll changed?! It's not like I was trying to fight over text message. We text every day and a lot of times he texts me first! It just made me sad because I felt like I was annoying him or something :(