I live in Fairless Hills, PA and have experienced the feeling that I awaken at night in my bed and I can feel a slight vibration, it's usually what wakes me up because I am a light sleeper. I don't feel like I am shaky or shaking, (and my heart isn't beating abnormally that I can tell, not racing or anything) but that the bed is and I have reached out and put my palm down on the bed and can feel a light vibration.
I thought it was a tremor or very small earthquake or possibly the nearby loading facility for the freight cars.
Dear Andrew: your symptoms are suspicious for an arrhythmia. From what you describe, I think you might have a supraventricular tachycardia (SVT), which is a broad term that covers many different types of arrhythmias. If you do not feel poorly during these episodes, then it is not an emergency to get seen by a doctor right away. However, I would strongly recommend that you make an appointment with your doctor to get an “event monitor”, similar to a holter. It would monitor your heart beat and rhythm whenever you experience these symptoms and push a button to activate it. Your doctors can analyze the report and recommend next course of action. Good Luck!