Strange behaviour during unlocking

After being more than 6 months away from my car, I tried to get inside last week. The car was impossible to unlock with any of the 2 keys. Just wouldn't do thing as if the key batteries were dead. I tried with the emergency key in the key hole. I could only turn it in one direction. The emergency lights would flash twice on the car, but it would remain close. nothing else. I finally managed to unlock the car by holding the key on the windshield, as close as possible to the steering column. The car then started normally and no more issue since then.
It looks like after some time, the car gets into a sleeping mode, and this can only be deactivated by getting the car key close enough to the steering column.
Anybody else has experienced that, or know anything about it?
Cheers,
Max