Smart contract gas used increase by 3 point every tx

Hi.
Here is my SC KT1UmL8Z..2kxKpx on tzkt.io
I just noticed that every tx gas used increase exactly by 3.
Is someone having any explication ?
Thnaks in advance guys.
Chill8ut.

The increase in gas cost probably comes from the increase of the size of your contract’s storage.

Hey @rafoo , thanks for your answer.