This could happen when the page changes admins, i.e the page gets sold to somebody on a trading forum / SEO forum, like blackhatworld. Some FB pages are very valuable, similar to the story of @N on twitter.
When a page changes hands/admins, there could be some political agenda pushed, or even a religious agenda. It could be another "best vines" page, who knows?
When this happens, the page jumps to the top of a person's likes, so as to notify the person of the new page contents.
Usually the page is left with no trace of previous posts. (All posts are wiped, but the likes remain)
Of course, now you're going to tell me you don't like any pages, and liked pages are conjured up from Facebook itself, which is highly unlikely, unless they are doing A/B testing on you, and you are simply a guinea pig, but again, unlikely.
This is deceptive on Facebook's part, because ... Facebook
It's nothing to worry about though. Simply unlike, and soldier on through your day.
