The normal range is 3.7-5.2 mEq/L, according to this article:
http://www.nlm.nih.gov/medlineplus/ency/article/003484.htm
so your 2.8 is definitely low. When it's too low, your heart can have various rhythm and electrical problems (such as 'flutters'), so they'll want to (a) find out why the potassium is low, and (b) fix it before any surgery.
Acid reflux can be caused by all kinds of things, but as far as I know, it's not directly related to low potassium.
If your electrolytes are off it can affect your heart rythm, which could account for the flutters. They probably just want to get it straightened out before they will do surgery. I don't know what the range is for potassium, but I'm guessing it was out of the normal range. Acid reflux often goes along with heart issues and can make the heart irritable. This is all personal experience. You should see your doctor sooner rather than later. Good luck.