I've been asked to repack by AA, when I showed up (in the USA) with bags weighing about 54lbs and about 25lbs. I just shifted a couple of things over and was thanked for being helpful. It was a strict interpretation of the rules, but done politely and reasonably.

I can't see much of a problem with that.

On the other hand, I've often been let off with a 1kg or 2lb over bag. I know I'm being let off, though.

If packing close to the weight limit, I highly recommend