Whilst we're talking about moving luggage I have a self DYKWIA to report from a few months back.

Was on a KL flight and when I boarded the baggage racks in EBC were completely full despite only being one gentleman in the whole cabin. I randomly moved one bag from the bin immediately above my seat to a bin further back in Y, but with my bad luck (and to be honest it was inconsiderate of me in the first place) looks like that was the gentleman's bag. (Or maybe they were all his...)

Follwing my example of not asking before acting (in which case I would gladly have put it back), the gentleman stood up and without a word, removed my bag and put it in in the Y cabin, then regrabbed his bag and put it back where it originally was, all whilst staring at me. Then only after this was all done, with a face flushed red with anger he said "Don't touch my things". I told him sheepishly that I was very sorry, but there was probably no salvaging our chance of ever becoming friends.