As an NHRA tech for Division 3, I can confirm, there has been a rule change for 2012, and the ribbon style nets ARE required to have SFI date tags and and are good for 2-years just like the seat belts. I don't fully agree with it, but that is now the rule.

I personalty talked with one of the head guys for SFI and he indicated they have found when testing belts and window nets that even if kept out of the sun and in good condition, they lose some of their strength just from aging.