From what I'm seen, you're correct on the whole. Older people seem to take longer to learn, whether it's flying or anything else, though as with all generalisations there are plenty of exceptions to that rule, in both directions.
I do find myself wondering if the expectations and attitude of the instructor don't have a certain amount to do with this. A friend of mine went for her first lesson at 70+, and seemed to be treated as though she was going for a little jaunt, not starting a PPL. I suggested she sit down with her instructor and explain things, but owing to unforeseen circumstances she only managed a couple more lessons, so I don't know if it would have helped.
Anyway, hours to solo doesn't seem to have a lot to do with how well you fly in the long run, and learning about patience never did anyone any harm, especially a pilot. Good luck, and I look forward to reading an account of your first solo soon!