I don't think it's down to interest in meeting new people. I am in my 30s would also describe myself as a sociable introvert. I would say it's about the appropriate context.
If I have joined a new club, or group activity, for example, I psych myself up to get through the small talk phase, which I hate, as I know that there's a good chance that there will be at least one or two people I actually click with. However, I hate the initial phase and find it draining, as I only really enjoy socialising with people who I have got to know well.
If I have arranged to meet an existing friend 1 on 1, or a very small group of friends, and then someone invites a random, I hate it, because it changes the dynamic to the shit, early, small-talk phase that I only ever endure in the hope of finding true friends.
It's more frustrating in that situation, as the chances that I am going to have so much in common with a single random mutual friend are very slim (it's never happened), and the chances that the random and the friend who invited them will talk about shared experiences, in-jokes etc. that don't include me are very high.