It has happened earlier but I can not recall any memories of these early warnings. Today I find it quite disturbing! Most of the times the warning comes just a fraction before my change of direction but still it interferes the dance rhythm, the natural flow of movements.
If the couple has been involved in several and severe bumps when the axes of the couples are shaking - then there is reason to interfere. But why should you do it in other cases?
Once when the pista was very crowded a follower commented: I opened my eyes and was frightened - the other couples were so near! I decided to keep the eyes closed during the rest of this tanda and the leader got to cope with the situation.