Do you plug and unplug that thing in frequently? The reason I ask is because what you are reporting is symptomatic of a lot of wear and tear.
If it turns out that indeed the AC port is out of line, then if you get it replaced I'd suggest that you consider leaving it plugged in permanently (to the computer that is, not the AC wall outlet.) Otherwise, if you continue to stress that connection out, it's only going to happen again sooner or later.
If that's not practical for you to do, then perhaps whenever you plug in the adapter, you can try and make sure you're plugging it straight in . . . 'cause every time you plug that thing in at an angle, you're stressing the connection. Probably good if you move the laptop so that you can see the port when you plug it in. Doing it "blind" increases the risk that you're going to shove it in at an angle.