my ex is flirting with me, 11 years after we broke up

So my ex, who was my first sexual encounter, hit on me today. We dated in high school for like 5 months, but we both got bored and I broke up with him. Fast forward 11 years later and while we have kept in touch and hung out from time to time, (he kissed me once like 6 years ago at a party, but he said it didn't mean anything, and that he wasn't looking to have sex or reconnect) well this morning he sent me a message on ******, and when he mentioned not being able to sleep I asked what was wrong and he answered by sending me a (hard) dick pick saying that's what is keeping him up. Maybe a mistake but I did send one back, he said he had to go to work soon and that was it.
Now all day I've been mulling it in my mind and I really don't know what to think, is this just him flirting because he is bored? wishful thinking on my part? I mean I regret what happened with us but we were kids, I'm having a hard time trying to figure out what his angle is, and how I feel about it. I will probably always have feeling for him given that he was my first, but I just feel like I'm too wrapped up in it to see things clearly, am I missing something obvious?