Tension in any part of the physical body will cause you to get stuck in those areas. There are ways to work with this- do more 'physical relaxation' in the first part of your routine, and/or use a 'distracting' method to separate when it feels like it's time to do it. That you are body-aware at this part of the exercise tells me you're not relaxed or tranced enough to start trying- perhaps you need to wait a bit longer, or use a method of separation that disengages your consciousness from your body, in other words, your attention needs to be more environmental and less body-centered.