The bubbles are odd. I'm wondering if those are remnants of his old exoskeleton that are just stuck on. Typically mantises throw a fit and obsessively groom if they have pieces of their exoskeleton left on them (not that there should be). The exoskeleton, however, should be fully shed when they molt and not have pieces left on the mantis. It's not very common for any pieces to stick if the humidity is right for the species.
Have you checked to see if the bubbles are just water droplets? Mantises usually get wet one way or another when you mist their enclosure.