You're talkig about what is called an 'embolism', which is when a bubble gets trapped within the plant's vascular tissue, analogous to a clogged artery in an animal.

This is not as common as the texts would have you believe.

The best way IMHO to prevent this is to give your donor plants [mothers] a heavy watering an hour before you take cuttings, so that they are just as plump and turgid as can be, already saturated with moisture, and get them dipped into your rooting hormone as SOON as you make the final cut.

You should be fine as soon as you stabilize the temperature of your cloning apparatus.