Heh. Funny that.
When I started carrying, I kept my StarTac flip phone in a belt holster on my right side.
Since that space was going to be taken up with pistol, the phone had to go to the left side. That was a bit of muscle memory I had to retrain.
But I can have pistol in one hand and phone in the other now, if need be.
I had the same issue. It all seems natural now.