Drama

So the other day I saw in my boyfriends phone he had gotten a message from an ex girlfriend at midnight, I did than snoop, it was a music video. He responded later in the day basically just answered her messages. They were together over ten years ago, they recently had a run in which is why I think she is messaging him. Anyway what my concern is I did ask him about it because I was concerned and he said to me he should of told me when she reached out he didn’t think anything of it. He said he didn’t even answer. I said “oh so you didn’t answer?” And he said “no, you can see the message if you want.” My Issue is that I did snoop, and he had answered. Really just one word answers but he still did. What would you guys think or do ?