In my plastic bottles there are bubbles on the top of them. If I shake the bottle and I move the liquid the bubbles still stay in the same place like as if they were glued to the bottle. I clean my bottles in the dishwater, or sometimes with hot water and soap, but after cleaning them I shake them with clear water for a long time, so there not should be rests of soap. Is this a normal thing or I am doing something wrong? Thanks guys
