When you planed the door down did you manage to plane it square? If you didnt and the bevel you created is on the inside of the rebate it would hit the frame before the door is fully closed causing it to "bind"
Take the door off and check it with a square
If you have turned the door completely around its probably a case that the leading edge is bevelled the wrong way on the hinge side, so dispite the fact that you have a 2mm gap visable down the hinge side of the frame, The other edge could well be binding on the frame?
Lack of a leading edge on the hinge side combined with a little swelling should also not be ruled out.
If you are taking the door off, Take the oppertunity to stain/paint the bottom of the door