vtkCurvatures yields unreasonably large values along borders

Here are the bands with ranges and frequencies. I have just split the data into 10 bins so you can see the distribution.

Gaussian Curvature:

    cc = ComputeCurvatures(source)
    cc.set_gauss_curvature_bounds(-0.5, 1.0)
    cc.gauss_bounds_on()

Bands & frequencies:
   0 [  -0.500,   -0.425,   -0.350]:    290
   1 [  -0.350,   -0.275,   -0.200]:    208
   2 [  -0.200,   -0.125,   -0.050]:    358
   3 [  -0.050,    0.025,    0.100]:    684
   4 [   0.100,    0.175,    0.250]:    829
   5 [   0.250,    0.325,    0.400]:    769
   6 [   0.400,    0.475,    0.550]:    610
   7 [   0.550,    0.625,    0.700]:    501
   8 [   0.700,    0.775,    0.850]:    372
   9 [   0.850,    0.925,    1.000]:    247

Mean Curvature:

No bounds set for the mean curvature so all the adjusted curvatures are used.

Bands & frequencies:
   0 [  -6.868,   -6.375,   -5.881]:      1
   1 [  -5.881,   -5.388,   -4.895]:      2
   2 [  -4.895,   -4.402,   -3.909]:      1
   3 [  -3.909,   -3.416,   -2.923]:      3
   4 [  -2.923,   -2.429,   -1.936]:     11
   5 [  -1.936,   -1.443,   -0.950]:     44
   6 [  -0.950,   -0.457,    0.036]:   1141
   7 [   0.036,    0.530,    1.023]:   3699
   8 [   1.023,    1.516,    2.009]:    436
   9 [   2.009,    2.502,    2.995]:     19