Turn the power off then take the cover plate off.

Now look and see what's not secure. Sometimes the receptical can just be tightened down in the box.

That's not the problem. There was some wood panelling installed over the dry wall, so to bring the face of the outlet out so it's flush with the cover leaves room for the actual outlet to "bounce" I'm wondering if I can just use longer screws and some washers to fill in the space.

They make plastic spacers just for that. You can get them at home depot along with the longer screws.

The reason I suggested taking the plate off and looking at it was because you made it sound like you were unaware of the cause of the issue.

Thanks for the help and suggestin LarryG. Just what I needed.