(Me answering my own question)
Some more googling I was able to find:
How to check if current facebook user like a page using PHP SDK?
A php version of the same question.
In that case, I will be able to check out FQL's documentation to find out how to get this information.
I really don't want a permission popup from facebook to pop up, and I don't think I will need that to make this work. I will try that and add a comment to this answer if it works just like what I'm looking for.