umm possibly a balance thing with tags and pages. When I was penalised for this (and I'm pretty sure it was this as when they were removed I bounced back up) I had 405 tag pages and 200ish posts. Takeachance has got 12 pages and 20 tags, similar ratio.
Mathematically pages will be recurring all over the place depending on how the tags are spread out.
I don't know about the time thing. My site is a .co.uk and when the tag thing happened it was the panda update. The most recent one seems to be for me anyway a link devaluation.
I don't think tags have anything to do with this. My tag to post ratio is ungodly. I put 5 -7 tags per post and I have over 1800 post on most of my 35 blogs.