Thanks for the comments and thumb-love.
Pingson, I was kind of regretting saying that as soon as I hit it...too much sharing? Anyway, she's remarkable.
DeSense, that made me chuckle: I was working out exactly that arithmetic when I read Professor P's reply, and with the same mental image of a school maths exam!
Nah, I'm just ribbing you, I am in fact in a rather similar situation - I'm (soon) 45 and my wife is 31 (but note that I pass the rule with a whole year to spare )