Just Trying To Figure Out Why My Foot Would Vibrate

Just trying to figure out why my foot would vibrate like a cell phone. It vibrates for a couple seconds then stops for 4-5 seconds. The sensation lasts for several minutes and has happened a half dozen times in the past couple days. It doesn't hurt, it is just annoying. I just want to know if it is something I need to be overly concerned about. I am a 47 yo female that is about 20 pounds overweight.