Bigeminy during rest

Hello,

I am getting bigeminal pulse (where one is normal followed shortly by a premature heartbeat) during rest. This happens when the pulse is at lower speeds, especially when I wake up after sleep or sit down for longer. The rythm is like this: normal beat, premature, pause, normal beat, premature, pause.. It can continue like this until I start moving around. When the normal beat occurs, I can feel it in the chest (I believe this is due to pumping more blood due to requirement). The rythm can last for minutes and hours I believe.

I am on Nebilet and Cozaar for BP. I have just went trough eho, ekg and stress ekg. All went back fine but I did not have episodes of this rythm at that time.

What might be the cause for this? Thank you.