automatic shutting down Smart Key ?

Hello everybody, my GT has been standing in the garage for 1 week now and has not been moved since. Today I wanted to get something out of the car. Pushed the door button and nothing has done. Had surprised me already when going in into the garage, which he does not start with beeping.(Comfort opening tailgate) Even after repeatedly pressing the button on the handle no reaction. I already panicked because I thought battery was empty.And that with a new car … I wanted to start the K But I thought of it even more fortunately, which I also have a remote control … With this I was able to unlock without any problems. However, Smart Key still did not work. Only after several times closing/opening with the FB then also Smart Key worked again. Can this be that the Smart Key System shuts down itself with longer service life? Has someone ever happened like this? In order to have a manual ic However, it is not possible to find anything about this.