epipolar lines not parallel for rectified images

Question

I calculated the fundamental matrix of stereo view, I rectified both images using that fundamental matrix now the epipolar lines should be parallel to the x-axis to prove this, I calculate again the fundamental matrix for the rectified images to check if it gives F=[i]x the antisymmetric matrix representing the cross product with i

you can clearly see in the image that the marked points have the same y (height) however the epipolar lines arent' parallel:

F that I found is:

   F=[[ 1.89693346e-06 -1.75374506e-04 -2.16090418e-02]
     [ 1.99776626e-04 -1.71071653e-05 -1.89981986e-01]
     [ 2.16519377e-02  1.89151983e-01  1.00000000e+00]]