Tom Petty "I Should Have Known It"

Call it the "We're not old" single.

Have you noticed, that some of our favorite heritage artists, seem to want to prove that they can still kick ass?

Tom Petty has been making rock records for quite a long time, and he's got nothing to prove. But I suppose, if his new album led with a song with the tempo of "Free Fallin'" or "Wildflowers," some stupid reviewer would call him a middle-age folky.

To make sure that doesn't happen, the first single off his new record "Mojo" is the riff-heavy "I Should Have Known It," which sounds more Zeppelin than "Mary Jane's Last Dance."

Is the whole record going to be this heavy? Unlikely. Petty records tend to vary tempo and texture, so I'm betting this song is on the hard end of the spectrum.

Have you noticed this trend? Established, older, familiar artists, releasing the rockingest track on their new record, as a way to say "Don't call me soft."

Think "Supernatural Superserious," the first single off R.E.M.'s "Accelerate."

Think "Radio Nowhere," the first single off Bruce Springsteen's "Magic."

Think "Get On Your Boots," the first single off U2's "No Line On The Horizon."

None of these tracks are representative of the album they appear on. And none of them proved to be particularly durable---they didn't last on the charts as long as some of the later, better singles off those albums.

But they made a strong statement. Don't call it a comeback, indeed.