What does it mean, is a good question. Probably as you said, confirmation of where you are supposed to be, and that there is purpose (pattern means non-random, hence purposeful).

As for snake spirits, I "see" them in my photos in abundance. I have since learned that serpents have played a huge role in religious beliefs of earlier civilizations, such as the Sumerians, Egyptians, and Mayans, to name just a few. Serpents and spirituality are quite connected. One example is kundalini, the yogic philosophy of ancient India where spiritual energy is thought of as a coiled snake residing at the base of the spine that will rise up the spine upon full spiritual awakening.