Most NDAs are perpetual.
I totally understand not wanting to poke the legal behemoth, however.
As an anecdotal, a personal friend who is a former Googler signed a 10-year NDA, and he had his fingers in quite a few pies.
So maybe in 3 more years?
Do you have legal citations supporting this assertion? I'm fairly certain this isn't so.
As I said, I definitely understand not wanting to be the one to actually set precedent - that involves getting sued by Google, which is expensive and potentially career suicide. But I think ultimately its probably not enforceable.