Gregg Allman has postponed his planned book tour for health reasons.

Allman, 64, is scheduled to undergo heart tests on Friday at the Mayo Clinic in Jacksonville, Fla., the same facility where he underwent a liver transplant in June 2010.

The co-founder of the Allman Brothers Band, or ABB, recently had hernia surgery related to the transplant and said he feels as well as he has in some time, according to CBS News.

In a phone interview on Thursday, Allman told CBS News that he is experiencing arrhythmia, a problem with the rate or rhythm of the heartbeat.

It's just one of those make-sure tests, you know, Allman said. My heart goes into A Fib (atrial fibrillation) and does those beats -- you know, instead of going du-dun, du-dun, du-dun, it goes ta-da-dat-ta-da-doot-doot. There's a little reggae in there somewhere.

The ABB website recently posted an update on Allman's condition, assuring fans the singer/songwriter intends to follow through with the planned tour: We wanted to let everyone know that Gregg is excited for the book launch and is still planning to get out on the road starting May 8th. We'll be posting updates regularly. Let's all send positive vibes Gregg's way!

The postponement follows Allman's absence during one of the ABB's recent residency shows at the Beacon Theatre in New York.

Allman left the stage during the second set of the March 25 show because of bulging discs in his back, according to the group's website. [Allman] had a painful flare up 30 minutes before the end of the second set at the Beacon, which forced him to leave the stage, the website said.

The book tour to promote his memoir, My Cross to Bear, will go on as planned, beginning May 8, as long as doctors find no serious problems.

I know there's been a lot of people that have had their hearts set -- God bless 'em -- on seeing me and my boys perform and seeing me and the Brothers perform, Allman said.

And because of this virus and all these damned surgeries, I had to cancel. I've always really held that sacred, and a no-show I am not. I'd like extend my apology to them. It's just kind of a bigger bump than I expected in the road, and as of this summer I'll be there with bells on in the future.