Trust me, it is a good thing!!!
When you go into meditation, yoga, walking or even during times of being still, basically doing something that you love and gives you peace and calm, you are reaching a higher vibration within your body. You are subconsciously grounding more deeply which creates the energies to flow into you from the Earth. You are a open channel to receive energies from the Earth from below and from the Divine from above into your crown chakra. If these chakras are open even a little bit, it will be felt. The more that you practice what puts you in the state of peace, calm and love, the more these channels open to receive more energy.
Also, the super cool thing is that your Kundalini awakens with practice of what gives you the state of calm. It is like a serpent uncoiling from your root chakra all the way up past your crown chakra. This causes the sensation of a very strong current flowing thru your body and out the top of your head.
It can sometimes feel orgasmic as well.
I have had a few people tell me that they were told by spiritual teachers that this is all a bad thing, that it isn't normal for this to happen. We are all on a different blueprint awakening at altering times and on different vibrational levels. We all hold a piece of the cosmic puzzle.
Always remember that if the teacher never experiences what you do, doesn't mean it's wrong or a bad thing....it just means that she/he has never experienced it before!
Now go sit on a rock or against a tree and practice hearing no words inside your head.....awaken those energies within!!!