Some advice please

I have recently reconciled with my boyfriend of 5 years after a 6 month break. It's only been 2 weeks and I think he's cheating on me already. Last night he got cross because I asked him a few questions about our future together - at the time I was a little perplexed and didn't really know what to say. However, this morning, I think I have driven past him on my way to work. I was leaving the town we live in, he was heading towards it. Usually, he doesn't text me in the morning, I always text first but this morning he has text me. I am not sure it was him but I do know his car and because he has text it leads me to believe that he's feeling guilty or wondering if I saw him. Does anyone have any advice? Should I say that I thought I passed him or should I just forget it as it's such early days in our reformed relationship? I am also wondering if he was deliberately trying to start an argument so that he could go and see this other person. He did get a message on his phone last night, which not long after receiving, he was saying I should go home.