No, you got a cheeky answer, we would maybe say "Ho quattro anni più di te" if we really didn't want to just say "35" (or whatever his age is).

it's not typical. The typical answer is "ho quattro anni più di te" or "sono quattro anni più vecchio di te" or "quando sei nato io avevo già quattro anni". "Io ho vissuto quattro estati più di te" is an unusual answer, I wouldn't suggest you use it if you don't want to look odd.

OH! Is this perhaps a regional expression? '40 primavere' or a more antiquated term? Curious that no one else recognized this paraphrased expression. So glad you chimed in. THANKS! (My friend fascinates me more and more so I keep diving into these cultural mysteries)

Hi, Virginia. In Italy sometimes, to indicate the age, we use the number of "springs" (for example: "La signora ha 40 primavere"); so I think your friend has made a paraphrase of this expression!

You make a very interesting point A?P about the Native Americans. And it is poignant to me. I marked this question in relating to CULTURE though. So I do believe it is appropriate. :)