Water will bead on newly stained wood boards. This phoenomenon will not last forever on a very exposed deck.  By exposed I am referring to decks that get a real good amount of hot sun on a daily basis, AND/OR decks that are susceptible to lots of rain with perhaps limited or no drying times in between.  The water beading in these pics are from a transparent stain job four years ago. This happens to be a covered porch area, protected from sun and rain!!

The reason that water is beading on these very old wood boards is because this is a fresh coat of stain.