First off, wrong forum, should be in Rules Questions
Second, yes, they absolutely could perform a combat maneuver easier than attacking you. This is as designed, and makes perfect sense.
Remember, your AC includes your armor, your dex, and other bonuses (like rings, dodge bonuses, etc). Your touch ac, on the other hand, I'm sure is lower than your CMD. It's a lot easier to touch you than it is to shove a sword in your gut. By the same token, it's easier to grab or trip you than it is to shove a sword through your guts. Mainly due to that armor you are wearing deflecting the blade. That shiny armor, however, does nothing to keep you on your feet, or keep you from having your sword knocked out of your hands, or stop you from being grabbed by someone.
My AC is 23, my CMD is 22, does that mean someone could pull a CMD based attack and trip/grapple/etc even if they cant actually touch me?
Pathfinder uses an abstract combat system. The fact that your enemy did not beat your AC doesn't mean they didn't touch you, it just means they failed to do hit point damage. They might have hit you but failed to penetrate your armor, for instance.
CMD is your ability to avoid being tripped, or having your weapon twisted out of you hand, etc. It has nothing to do with your armor, and can definitely be easier to pull off than actually hurting you, depending on your armor and class.