Re: Changing heads question
I suspect that you are right and that the head wasn't seated and was also unevenly tensioned. As long as you didn't have it on long or really cranked the crap out of it, you should be able to reseat it and tension it evenly and it shouldn't permanently damage the head.
You mentioned a difference of an inch (!!) between one side and another...I hope that is just an exaggeration because a head that stretched on one side but not the other would have been easy to spot before you put it on. Normally, there may be a little bit of play and/or unevenness, but nowhere near what you are describing. Modern manufacturing techniques and quality control are usually pretty good but there are always slip-ups that get through, though.