I haven't had that experience, but it reminded me of a story I heard on NPR once. Apparently there's a rare condition where some people whose vision can't perceive depth, this one woman was undergoing some kind of experimental treatment (I think it was not medical, but more like physical therapy for eye muscles), and she walked outside into falling snow, and the first thing she ever saw in 3D in her life was falling snowflakes. And of course she was stunned into stillness, just stood there watching for a long time.