Thanks Purk, that happened to me a couple of times without the damage part. These posts made me go look in a drawer full of portable audio stuff and I found a replacement cable for JH 13 that I think I bought when Marc built me a Fetastic Amp with a special connector for balanced JH13 usage. Anyway, I put on the new cable and the fit is much tighter and better.
The odd thing was when I plugged into my iPhone to test it -- the bass was WAY stronger and practically bloated compared to my recent JH13 listening. I played some bass-heavy Cowboy Junkies while doing some chores and couldn't shake the feeling that it was markedly different with the new cable. Without taking out the JH13s, I unplugged the new cable and put the old one in place, which was not easy to accomplish. There was definitely a difference --maybe not as extreme as I was first thinking but certainly there and pretty pronounced. I am assuming the lousy connection and slightly bent connector on the left side have more to do with it than a different cable but I am mostly just happy that I had the replacement already in hand and don't have to worry about the JH13s getting stepped on the next time I am getting off an airplane or whatever.