what does it mean when your solar plexus area is vibrating?

When I've meditated in the past, I experienced sensations of my lower abdomen vibrating. I once was awakened at night because my whole body was vibrating. I haven't meditated in a while because work is too busy lately. However, one day last week while at work, my lower abdomen was vibrating again. This went on for about 2 days. Anyone who knows about Chakras and vibration, can you tell me if this is my spiritual body trying to tell me something or is this just a random event?