Facebook glitch on Windows Phone?

Recently I've started seeing every person-to-person wall post in my news feed on Windows Phone. This is both inside the official Facebook app and in the People Hub. It used to only show these messages if both people were my friends, and that appears to still be the behavior on the website and the Windows 8 app, but now I'm seeing all of them if only one of those people are my friend. This results in a giant wall of Happy Birthdays from people I've never heard of about once a week, rendering my Facebook feed unusable.

Is there any way to fix this? Is it a known issue or have I done something weird?