I used to need to be around people, at parties, at clubs, etc....But in the last 10 years or so, I've become the complete opposite. The last band I played in sent me almost into a depression. One of the reasons was that I hated the music we played, but the other reason was how much it would give me anxiety attacks to leave the house on a Friday to go play.
You're not the only one!
My explanation to people is...
"I've grown comfortable in my solitude." 
Hey...I see way more people than I want to at my day gig...and work is cool, it's a pretty mellow/friendly attitude, so there's also plenty of socializing too.
When I leave work and come home....these days I don't even want to walk up my driveway to the mailbox once I'm in my house.

I just don't really go out much anymore....once in awhile to hear someone play, but even that's rare....and usually I'm the same way, the anxiety of having to stop everything and make an effort to go out is a PITA. When I have to do an overnight somewhere, like go visit my sister who is too far for a day trip...man, it's not a happy thing for me (not the being there, but the leaving my own house part).
I've become an absolute homebody...and I'm quite comfortable with that.
Back to the thread....
So I'm sitting here wondering....how the fuck didn't Sam and his "people" (I'm sure there were many involved in the recording/release of his music) not notice the similarity...???
It's not like the Petty tune was an obscure one. I would think someone in his inner music circle would have leaned over and said,
"Hey Sam...is it me or does your chorus sound a lot like that Petty tune...?"
I mean....who was looking out for the guy...?
I hope that if ever I post a song that sounds like something already out there...you guys will say something.
Even if my tunes never see dime-one....I still don't want to have anything that sounds like an obvious copycat.