It means that you are letting go of resistance. Sometimes you can also experience heat going through your body, convulsions or similar type of sensations. It's all natural and well. There is nothing to worry about. Just let all sensations be as they want to be.

I experience those things often during mediation or other types of vibrational work. I found out that they often are signs of spiritual growth. Afterwards I usually feel better or get some kind of insight.

I get that often when I do Two Hands Touching, and so does my son. Sometimes it's pretty intense. It feels like something is changing on a cellular level. Like I am moving into a higher vibration. Like my physical body is responding to the THT by its self or with affirmations or EZ Deletion Sequence.