Oh it's a totally recognizable song! When I went and specifically pulled it out to listen to by its lonesome, I sort of sat back and analyzed why I hadn't connected it up. And I realized that when I was listening to the mix at work, I don't glance at iTunes to see details on the songs usually. And I already know Hey Ya and love the original (it grew on me, after I hated it at first... it's one of those songs which all of a sudden something clicked and I was like I HAVE TO OWN THIS). The cover isn't so significantly different from the original that my brain couldn't do a "I know and love this" and I just smiled happily when it came on, sang along, and hadn't quite twigged onto consciously that it was a cover.

What's scary is how often this happens. There's one song that I just realized last weekend was Simple Plan that I had thought for almost a year was Angels & Airwaves, because I first heard it in a mix that included both bands, and the SOUND is very much like A&A. So until I was listening very specifically to the Simple Plan disk, I just lumped it in with A&A.

My brain has a habit of doing more pattern recognition where music is concerned, and less actual memory and noting of details. *wry smiles*