It can be both. If your site had been manually penalized, you'd maybe get a message in Webmaster Tools(assuming you are using it) about it.

As you have only moved from page 1 to page 2 for your keywords, I think it's highly unlikely you have been penalized, and it's just an automatic result of the recent algorithm changes.

Page 1 to page 2 isn't so bad compared to some of the horror stories I've read on here and elsewhere, so by looking at your backlink profile(and cleaning it up/improving it if needed), your on-page SEO then adding more content and building more quality links, you could get back to the first page for those keywords There's absolutely no way I'd advise you to do a 301 redirect.

I am not sure I would consider dropping from page 1 to 2 a penalty, it sounds like to me just a slight shuffle in the SERP based on the algo change. What I am saying is you did not get penalized just those sites ranked higher or you took a slight hit during it. All you have to do really is increase the strength of your backlinks and you should be able to easily get back to page 1.

If you were penalized, you would be on page 500 or not even showing up.

Penalized means your website drop in ranking.