@ken, my favorite method for determining if something is a linear plating bubble is to depress it with the tip of a wooden toothpick. Most of the time, that will flatten them. If not, then it might be debris caught under the plating.
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz