Held my boyfriend’s phone and grabbed it from me?

I was holding my boyfriend’s phone while he was driving because I was giving him directions. While I was holding it and looking at it, he became suspicious and immediately grabbed it from me and saw what I was looking at, which was the MAPS!

I said what’s wrong with you? And he said oh well you had a smile on your face while looking at the phone. Which I didn’t, I just always have a natural grin on my face???

Also in the past I’ve caught him msg’ing girls but this was years ago so I’ve tried to move past it. I just don’t want to get hurt again and I don’t know if I should read into this too much