I started dancing at 50 and it was the best thing I ever did. Most of the people who do ballroom in my area are around my age and, in any case, age doesn't matter. There's no stigma about dancing with people younger or older in classes or at socials. One thing to check, though, is whether the classes at the rec centr rotate partners throughout the class. Most classes do, but I did run into a class at my local Y that didn't. People who came to class by themselves got partnered up with someone, but then had to dance exclusively with that person for the 8 weeks of the class. I don't recommend a class like that; you learn much more if you rotate partners.