You are not the least bit odd----just perhaps slightly over observant. The cure is to work on finding better uses for your time. You could, for instance, ponder the several possible reasons for the use of the larger screw----all the while remembering the simplest explanation is often the best explanation. That said, how about this one? The workman had only three matching screws for this four screw job. He lit out for the hardware store as soon as he noticed this, but they were closed when he got there. One moral of this story is he should have called instead of spending his time and gasoline driving to the hardware store. Had he done this, he would have had enough time to chuck up a larger screw he had, and cut it down a bit.
As it is now, he's going to learn he's been found out----and very likely die of a guilty conscience-----and it's ALL YOUR FAULT!!!
RCT