I don't think it's a matter of maturing as much as it is a matter of where you are in your life.
Odds are, if you are currently working, you are spending most of your days dealing with people. Having a young family is that much more demanding on your "socialness". People are everywhere you turn, all the time. Finding a moment to yourself is difficult, if not impossible. Going out to meet and socialize with even more people is not likely to be at the top of your list.
However, if you are currently retired, you don't have those days filled with people wanting/needing things. Kids are grown and gone, and so are the social requirements that go along with having kids. So your socialness has been reduced to a great extent. Going out and meeting new people is a more enjoyable thing.
1975 American Clipper RV with Dodge 360 (photo in profile)
1998 American Clipper Fold n Roll Folding Trailer
Both born in Morgan Hill, CA to Irv Perch (Daddy of the Aristocrat trailers)