I (19F) can't stop thinking about what my boyfriend (29M) said about a picture of me?

We've been together for around 3 months. Recently, we were messaging each other and sending pictures of each other from when we were little as a way of bonding. One of the pictures was of me when I was around 13 years old, in skinny jeans, posing with my back towards the camera to try to be "sexy" in a dorky way. When we met up to hang out, I saw him staring at that photo on his phone. Then he said: "what does this photo make me kinda feel --" and then he paused and gave me a bit of a shy smile, which made me think that he was turned on. I said: "what do you mean?" And he answered: "anyways, never mind", and he switched topics to carry on with the activity we were doing.

Thinking back, I don't know exactly what he meant by that and if what he said was appropriate. For context, I don't look much different from when I was thirteen, except for being more "physically developed" in certain areas lol.