What do I have to be guilty about?

Today was going so well, I was in a good mood, despite being a full clinic day and looking forward to having dinner with Heath. I sent him a message stating that I would be leaving around 5:15. Luckily, I was able to leave around 5:00. Well traffic was horrible and around 5:20, Heath calls wondering where I am. Just a note, it takes me longer than 5 minutes to get home. It takes about 25 minutes. I told him I was on my way and would be home in about 10 minutes. He called back, which I somehow missed the call and left a message stating it apparently was not a good day to meet for dinner. I called him back and persuaded him to turn his car around and come back to my house. Once at my house, he told me that I sounded guilty and he was not pleased with this guilt-ridden tone. Well, since I had nothing to be guilty for, I was a little upset. We did go out for dinner, but it was very quiet. I don't know what is going on, but I wish he would clue me in.