ok
in part of a circuit you are doing a descending turn to the left.
since this is not far from the ground it is important that you dont stall there.
in the descending turn the left wing is flying slower and has a higher angle of attack than the right side wing. thus the left wing is closer to the stall.
so it make sense to place the stall warning on the left wing.
next time you turn finals just remember that the designer did his best to help you avoid stalling in that turn. the rest is up to you.