I have no problem with Alex's age. I just wish they had tried to make Rick look a little older. He did not have the haircut of a 40-50 year old man.
Thats the only problem. Evie looked liked she could be luke Fords mother.(she was 40 during filming) But Rick needed at least grey hair. That would have made it more believable. Maybe if there is another film they will address that.