The bubbles are normal. You won't get rid of them. I've glued hundreds of calls. The tiny bubbles are a process of the glue hardening. It's venting the gases as it dries hard. Just like paint does. As it dries, it releases the gas. With paint on cars etc, the gases escape to atmosphere. In building a call, you trap those gases from being released under the glass. All you can do is turn the glass about a 1/4 turn to even out what squeezes out from under the glass and over the glue land.