Blind Spot Assistant behaves suspiciously

Hello people, short introduction: After 1 polo and 3 gulf I became the brand “abtrünnig” and got me 3 weeks ago a new FR with the 1.5 l TSI engine. I like above all the look of the Arona, but also its good room layout. On the topic: Since a few days, quite exactly at 1,500 km it occurred to me for the first time. Before that however, I never drove so fast. Anyway, at 150, 160 km/h on the highway, the blind spot light in the driver’s exterior mirror first for c a. 3 seconds permanently on, after that it flickers extremely nervously for about 2 seconds and is quiet again. All this, although no vehicle drives far and wide, except mine of course. Does one of you know that? In addition, both blind spot lights, so left and right, go at the engine start for about 2 seconds, whereby I think this is a self-test and thus normal (?)