Everything is just so slow on G right now, and I haven't had a deep crawl since January 9. The pages are getting cached very intermittently, a couple of pages are crawled here and there, but not a deep spidering.
The pages that are being cached very intermittently, have they not been changed for a while? That may be why the cached page is not being updated very frequently. Google may be using their resources for pages that are being changed more often.