Why do bubbles form on the inside of a glass or jug of water when it is left for a while?

Dissolved gasses are released by changes in pressure and temperature.

As the water warms up to adapt to the room temperature, the solubility of air decreases, and air comes out of solution, in some cases forming bubbles. Excluding the surface of the water, this will happen most often at the interface between the container and the water, where the water is warmest.

Oh, that was a much better answer! 5 points!

Thank you! It makes so much sense now.