This heat sensation is very common in the nail industry and is called exothermic reaction. The heat spike is a result of chemical bonds being formed during the curing process. It happens when molecules in gel polish release more energy than is needed to cure.
There are two solutions you can use to help avoid this from happening to you. The first is to make sure you do not over buff your natural nails. A thin nail bed will become more sensitive resulting in a deeper heat sensation. Secondly, apply thin coats. The less gel there is, there less molecules there are to react and release heat.
If these two solutions do not work for you, you can pull your hand away from the lamp and wait a few seconds to slow the curing process before reinserting your hand again. However, do not worry as this is just an uncomfortable feeling and is not at all damaging.