I went to put a bottle of brew demon amber ale in the fridge and noticed the top of the neck inside the bottle looked like it was sweating .It was one of the mr beer 1 litre pet bottles Do i need to worry.Room has been around 69 to 70 degrees.I did notice it wasnt as filled as much as other bottles it must have been my last bottle before i ran out of beer but it was filled like 90% right to where neck starts.I dont see this in any of my other bottles