I've detected some in my toothpaste as well. Strange.
Good one. On a more serious note, I've been making my own toothpaste for quite a while now. For those glancing through this thread, the primary two ingredients are hydrogen peroxide and baking soda. I add peppermint oil and now and then non-iodized sea salt. I suppose one could substitute water for hydrogen peroxide in a pinch, but it would have to be reverse osmosis, spring/well, or distilled. Otherwise, you're back with the fluoride issue you're trying to avoid in the first place.