To date, I have never had an air bubble with the air hose clamping method (which I use for my adult bows), but I have had a few air bubbles using the inner tube type form (which I use for some light weight kid bows). I have wondered if it was caused by a lack of clamp pressure from the inner tubes or if perhaps there was something on the limbs that may have "soiled" the lamination...or if it was moisture in the laminations that evaporated when in the heat box creating a air pocket. Regardless...I haven't seen that happen in the last several bows I made even using the inner tube method on my youth bow form, so I suspect I did something wrong in some way or another...but, since then I have been using more rubber straps in order to increase the pressure on that form.
Anyway...just thought I would share my experience and thoughts on the matter.
Regardless, it is a very nice looking bow and I am sure your Dad will be very pleased with it.