Track keeping assistant works without being activated?

When I wanted to switch to the left-hand side lane in the city before a crossing, my car automatically turned back and turned off the warning sound as if the lane hold assistant was active. However, since I always turn it off immediately at the start of the engine, it could not have been activated, I had also looked, but it was switched off. I also flashed when changing lanes, why there should be no reason for a warning of the assistant at first. Does any of you, and is it worth a walk to the friendly? Thank you in advance for the answers