That is pretty common place if the HW has been on a vine for a while before being eaten. I try to hand feed HWs because of how good of a grip they have. If I do place the worm on a vine I make sure i get the cham interested enough so he will finish off the worm before it glues itself to the vine or plant.
One time Fred shot at one and it wouldn't let go of the leaf it was on. He ended up eating an entire pothos leaf and the worm...... He didn't feel the need to eat for about two or three days with all that in him LOL
The other thing you need to worry about with HWs are them biting the cham and gripping the side of the cham's mouth. Lenny has eaten a couple of HWs and when chewing the worm was able to grip his lip and he had to try hard to get the worm out of his mouth.