Change in the axis of the eye

[Disanz]

My eye prescription in 2011
Right eye-  SPH: -5.5, CYL: 0, AXIS: 0
Left eye-   SPH; -5.0, CYL: -0.5, AXIS: 90

prescription in 2014
Right eye-  SPH: -5.5, CYL: 0,  AXIS: 0
Left eye-   SPH;  -5.0,  CYL: -0.5,  AXIS: 180

both the spherical and cylindrical powers haven;t changed but the axis of my left eye has changed from 90 to 180. Is it a cause of concern?

I have been using the same glasses since 2011, and since my axis has changed, do i need new glasses?