I did a few side fence installs last month and both had the same issue where the gate just starts to drag. The standard two-way hinges help, but if the post moves even a little, it's toast. I started adding a little kicker bar from the latch side of the gate up to the top hinge post, cut at an angle. It's not pretty, but man, it stops the swing weight from pulling everything out of line. You just bolt it on after the gate is hung. Might be a bit overkill for some, but it saves a call back. Saves me a headache, anyway.