What would cause my spirit run to come out dark?

While doing a spirit run (rum) the foreshots came alright, but once I got to the heads everything went wrong. The output went from crystal clear to the color of my wash (dark brown). Once it started to style a bit, I could actually see a bit of yeast in my collection jars. I kind of believe it was because I had my heat up way too high in the beginning. Any ideas?