It is normal.The air pump in the process of rotation will be hot, so the air is hot, after the cold contraction of the gas volume will be smaller. In addition, the inflatable bed is PVC material, with strong flexibility and elasticity, after a period of time, there will be some expansion volume larger. The gas shrinks, and the bed gets bigger -- you'll feel a little softer, and a little more air will do the job.

If there is a lot of air leakage, please check whether the lid is properly closed. 

Cover is divided into three layers:

The first layer, the largest cover, has white inward arrows on both sides. This cover is used for air release. When you hear two clicks on the left and right sides, it means that the lock is tight;

The second layer, there are two signs of lock, one is to unlock, and one is to lock. According to the arrow direction, screw to the lock position;

The third layer, the top layer, is used for aeration. It is pulled out through a short strip and pressed in with the thumb, making sure it reaches the end.