P.S. Seems I had fixed the layer shifting issue by accident.
I was watching a u-tube video about regular maintenance of a 3D printer. It came to the part about hot end. It said about making sure the hot ed is "properly" tighten so that it will move freely left and right but not up and down.
I checked mine and found it a little loose. I could move it up and down with my hand. So, I tighten it. After that, the layer shifting seems to go away.
Knock on wood!!!