How to avoid little air bubbles in high gloss trim paint on doors?

I don't know if this will help you, but here's an article about why bubbles can happen. From what you said, it seems like you did most of them right. Click below to read it and see what you think. Wishing you the best.

http://living.thebump.com/stop-air-bubbles-house-paint-9475.html

http://homeguides.sfgate.com/tiny-bubbles-wall-painting-43006.html

You can minimize paint bubbles by using a high quality roller. This is one place not to cut costs. Additionally, don't have too much or too little on the roller, and take your time in application.

Thanks! I am now testing different roller covers vs. foam on scrap to make sure I get it right before moving on to the fronts of the doors.

If it is a smooth surface you will need a roller with no knap which will prevent the orange peel bumps. Always roll into wet paint and watch for drips. And as Erin said above, take your time