Cache Date 1969?

[rankme]

A good number of client's site pages have cache dates of Dec 31, 1969. They are new-ish pages from the past few months.

I'm trying to ascertain the reason for SERP drop and have noticed domain/redirect problems...google may think we're duping content.

Trying to figure out if there is some correlation going on here b/t weird cache dates and the 'incorrect' domain names. It's a recent problem (max 3 months out).

Any thoughts?