The in and out movement of the hands causes the energy surrounding them to accumulate between them, making it more perceptible to you. The hands are becoming more sensitive to the subtle energies.
As the hands become more sensitive, you can use them to detect the auric energies emanating from other parts of the body as well. These detections may feel like heat, pressure, tingling etc.
Hold your dominant hand about a foot and a half above your bared forearm. Slowly lower your hand toward the forearm. Pay attention to anything that you might feel. How close do you come to the forearm before you can feel the energy from it? Remember that the feeling may be one of pressure, heat, coolness, thickness etc. It will feel much like what you experienced between you hands. It may not be as strong, but you should be able to feel it. If you cannot, slowly repeat it. Remember that you are reawakening your ability to consciously be aware of the subtle energies around you.