It’s odd that the recommended service interval on my CLS550 2014 is 60K before you change the engine air filter. That’s such an ambiguous interval. If you live in a dusty environment you should do it much more frequently. As another commenter said, that filter you pulled wasn’t dirty at all. For the cost of these things, I’d have run a vacuum over that one, cleaned the air box out and called it good. What engine does your 2012 have? Have you had any oil leaks?