Beyond the Blue

My 2018 A3 saloon is not fitted with the lane departure system that vibrates or corrects the steering wheel, however today I've noticed 2 beeps whenever l changed lanes on the motorway. I've looked it up in the manual and can't find anything except details of the full system. Anyone else get this?

I'm wondering if there is such a thing as a sliding seat adjustment stop?This is my first Audi and find that the manual sliding seat rail has very small adjusting increments and me and the wife are forever trying to find where we had it set for each other. If there's no such thing I'm going to have to find a new wife with the same length of legs as mine.