Aren't the actors too old?

Rating: 7/10 (5 October 2008)

It really was a wonderful movie. I enjoyed it thoroughly. Great cast, and I loved the musical selections. I sang along and knew most of the words. Amanda Seyfried was just lovely, and very talented.
But weren't most of the actors at least 10 to 15 years too old to play the parts? If "Donna" was young enough to have her parents kick her out when she got pregnant, than at 21 years later, how could she be 59? Wouldn't she be pushing 40? The same goes for all the men who played Sophie's "Dad". Why were they ages 57, 55 and 48? I mean, I know it's just a Hollywood move, and we are supposed to pretend, but,
I'm just saying . . .