There are so very many possibilities, and the ultimate answer is yours, based on your own interpretation. If you believe it is your spirit animal, it may well be. Some may say that it could have been some glimpse of something in the astral -- or another -- plane.
There are also phenomena of the brain creating random thoughts when it is not being stimulated well enough. This can happen a lot during meditation. It's why so many worries of the day seem to occur while trying to sleep, and while meditating. An extreme method of inducing this sort of experience is with sensory deprivation. There are many methods, ranging from isolating one's self in a completely dark room for a time, to the use of an isolation chamber. People have reported some very bizarre experiences.