Should I be worried if my hands are shaking and my heartbeat is irregular 5 days after my triple bypass?

Yes! Post-op arrythmias are common, including atrial fib. Get to the er now, or call for a nurse or doctor if you are still admitted.
Treat the heartbeat. Five days out? Not uncommon to have both. "atrial fibrillation" a few days after"cabg" is about 20%, it is successfully treated with medication or other remedies. 5 days out i would assume it was picked up in hospital, if not let your physician know immediately because irregular heartbeat should not be untreated. Hands shaking? Let your body recover for a while, you had a big surgery.