Is this weird? all inner pages showing in serps

Ive been checking my serps like a hawk, and just noticed that for my main keyword half of page 2, all of page 3 and a bit of page 4 are only showing my inner pages!
it is an ecommerce about 1.5 years old, my homepage is still #1 page 1 as it has been for about a year
The last backlinking i have done to it was about a year ago and that was paid directory links in my niche and about 10 blog comments but nothing crazy

this is strange as it is a fairly competitive keyword and im starting to worry with all this penguin crap
has this happened to anyone else?

Ranked inner pages will help prop up your main page.

if your homepage for you site is still #1, what is the problem?

Im just worried as i have lost another website to the evil penguin 1.1
it was #3 now disapeared but all its inner pages are still ranking well
im just confused as to what is going on and trying to share info with the community, im guessing the more data we have the better!
also all my meta descriptions for those inner pages are pretty keyword stuffed so that goes against all the penguin talk that has been going on