With some water sources the water is more acidic. This then creates more molecular Hydrogen (the antioxidant) which is a gas. This gas has to get out of the UltraStream otherwise it will bulge and then leak. The gas pushes a little water out of the UltraStream which produces a drip. This drip will stop after a period of time.
This is not a leak, it is just the water in the UltraStream coming out, loaded with beneficial molecular hydrogen!