Looks like air bubles to Me. With Black or Brown Glass you would never know they were there.
There are several things that can cause this problem. One is not preparig the wood laminate properly before glue-up. Another is oil from the Bowyers fingers.
Usuly not caused from over clamping, or too much pressure, but rather from not enought pressure to distrubite the glue evenly. Also can be caused By the Bow form not being flat and square with the sides of the form.
Some woods will absorb the glue faster than other woods, the glue gets soaked into the wood laminate before it has a chance to bond and set-up with the "F" Glass....ONE SHOT...