Editor's Note: First Notes is a weekly update of recent happenings in the world of music.

* Robert Plant made a surprise appearance during Jack White's set at Lollapalooza Argentina. The Led Zeppelin singer helped White out for a cover of Zep's "The Lemon Song."

* A.J. Pero, drummer for the band Twisted Sister, died at age 55. It appears as though he had a massive heart attack on Friday.

* Tom DeLonge has offered a bit more insight into his split with Blink-182, stating that when he said, "I'm out," he only meant out of the proposed deal, not out of the band. DeLonge wasn't able to focus on Blink-182 because he's got a few other projects in the works.

* Nicki Minaj will peform her only scheduled Carolinas concert at PNC Music Pavilion on Aug. 4.