exactly!!!!!!! The Spiral Sun also represents elnlightenment and wisdom, both of which are words you could easily use to describe Zecora. Also, if you look at the mark a certain way, it resembles a swirling potion in a culdron over a blazing fire as seen from a top down perspective. Considering that the closest thing Zecora has to a special talent is alchemy, this would have to be one hell of a coincidence to be nothing more then a tribal tattoo. In fact, not only do I believe she has a cutie mark, I can proove she has a cutie mark. In "the journal of the two sisters" (which is cannon btw) sun butt and moon butt stumbled across a tribe of zebras on the edge of the Everfree Forest. As a direct quote from Luna's entry "Terribly exhausted from walking and not seeing anypony, I took to the air to find out where I was. Suddenly, I saw a village of huts and a group of ponies down on the ground. But as I grew closer, I saw that while THEY HAD CUTIE MARKS, they weren't exactly ponies. They were unusually covered with stripes." So, yeah, Zebra cutie marks have been confirmed as cannon.
It's an interesting theory, but I don't agree. I've always thought of the zebra's in a similar way to how I think of the chrystal ponies. If you'll recall, the Chrystal Ponies all have cutie marks dispite not being Earth Ponies, Unicorns or Pegasi in a traditional sense, because thier technically just a different kind of Earth Pony. I bilieve it's a similar situation with the zebra's. Thier bassically a different looking kind of Earth Pony. I think Chrystal Ponies, Earth ponies and, of course, zebras are all the same race (dispite looking very different) in the same way Chiwawas, German Shepperds, and Golden Retrievers are all dogs (dispite looking very different).