When glass is tinted, a slip solution is used to help in cleaning  the glass properly, applicating and positioning of the tint. When excess water is then removed with a squeegee, there is  a fine vapour of moisture left behind under the tint. 

Not visible at first the water vapour may begin to "pool" due to natural surface tension. This is a natural process that occurs in water molecules. 

This will be noticeable from both outside and inside. This moisture will evaporate over 2-5 days depending on heat exposure. More sun = faster drying. Cold or rainy weather will slow down this process!

 The thicker the tint -the  slower the drying time and tint may appear cloudy. 

One thing you can be sure of : Window Tint ALWAYS dries out.