I get intense contractions and tension between my eyebrows during meditation. Often these sensation are present at other times also, but they intensify during meditation. There is also a sudden relaxation of it with a clicking "sound" (can't actually hear it but it feels like a sound) - but it never fully relaxes and I tend to be unable to sustain my meditation session beyond 40-45 minutes because of this. I know the theoretical answer is to look into the nature of the sensation objectively and notice my reactivity, but I find myself wondering if I'm doing something wrong or if there is something about my life situation that needs resolution.
PS: I mainly practice Anapana/Vipassana as taught by S N Goenka.