Is it unusual ?

Is it unusual to get tired a year after triple bypass ?  Sometimes I'll still nap after sleeping 8 hours.

[Quadruple]

Yes. Your normal.
I use to sleep over 10 hours and still take a nap in the afternoon.
I only noticed it the for the first few months.
It's good to sleep, it helps in your recovery.
It would only be a problem if your sleeping more then 12 hours a day.
If it's over 12 hours a day, call your doctor.

After a few months, I noticed I was having an issue with having NO energy to do anything.
And this turned out to be the High Blood Pressure meds that was taking all my energy away. The doctor then adjusted my dosage a few months after to help me sort it out. I'm on Carvediilol (aka Coreg) it and other HP meds will effect the energy that you have.