Google New Cache - Google Old Cache

Onces it's there, then its not

[layer8]

I have been waiting for Google to update for ages (nothing new there) but I have seen them going back in time.

My old site cache was dated 2nd August, then in the last 5 days I saw traces of a new cache (around 13 august).

Now I see the old cache back - has anyone seen this, is this normal - does not look like a regular thing cause I have never seen it revert back to old cache before.

I have tested on different data centres and can't find a trace on the new cache.