Ex-Colleague Suspicion?

Hey everyone, I had a colleague that I worked with the past summer. He is 2 years older than me and is wrapping up his UG career soon.

He appeared to be a decent co-worker and I never ran into any problems with him, never really second-guessed his intentions or the actions that he did. Honestly, I thought he was a genuine guy. However, he was about 2 years older and a little wiser when it came to the 'urgency' and 'anxiety' with recruiting relative to the younger guys. Honestly speaking, he came from a non-target school and he felt really insecure at the same time.

After we parted ways from that work the summer, I constantly see him checking up on my linkedin profile very frequently and I always asked myself 'whats up with this guy, why is he stalking me'. I met him again to grab drinks to catch up while all knowing that he was 'stalking' me the entire 8 months, I wanted to see how he was doing.

The conversation was pretty normal and to be honest, I could still sense that 'insecurity' from him when he was talking about the struggles he feels, and honestly, I could sympathize because now I was entering that stage too and reality is, there is a lot of uncertainty. However, midway to the conversation (mind you he is older), he was asking very suspicious questions and very specific ones that made me think that he was 'reaching' a little bit too far. He wanted to know all the nuts and bolts to the point where I would lose my competitive advantage in the marketplace. He would ask me about specific people that I knew but all this was not very organic also, it was almost as if he wanted to 'gain' something without 'giving' anything in return. I get it, it's a relationship-based business, but in the moment while I did open up a little bit, not revealing too much but just the surface level, in hindsight it seemed almost predatory and even this morning I open up linkedin to see him searching me again. Look now I am somewhat in the same boat as him with recruiting in full fledge but with him invading me with very suspicious questions and trying to 'gain' something without 'giving' anything in return makes me wary of this guy.

The question I have is, am I being too paranoid here? Am I just too competitive? Maybe I am both but don't tell me that when someone is trying to penetrate your intellectual property and gain something without having to give anything back is 'okay'. How have any of you guys dealt with a scenario? Would love all sorts of perspective on this.