Yeah, turning 40 is nothing. I remembered once when i turned 1300. Vaguely. It was when i read War and Peace for Russian Lit. At least i'm pretty sure it was more than 1300 pages long...
I admit i don't remember very much. I'll have to do it again sometime...
But really, it isn't you getting older, it's the rest of the world getting younger and perhaps a little bit more foolish. Hard to say...