Posted: Wed May 23, 2007 2:59 pm
It's the water degassing itself. Tap water will often contain dissolved gasses that will release/bubble up after it comes out of the tap for a few hours to a day. It's not much to worry about and should go away in a day or two. You can also wipe them off the glass and increase the turbulance at the water's surface to help gas exchange with the air.