I converted your data to a numpy array, it came in as a float32 (32bit floating point values).
I set the array type to float64 and a slice of it looked like this
a[100:300, 100:300]
Out[44]:
array([[1489.567, 1490.179, 1490.441, 1490.702, 1491.003, 1491.728, 1492.366,
1493.299, 1493.946, 1494.314, ..., 1639.082, 1639.969, 1640.586,
1641.29 , 1642.091, 1642.714, 1643.287, 1643.971, 1644.556, 1645.272],
[1490.182, 1490.748, 1491.255, 1491.775, 1492.324, 1492.644, 1493.596,
so I suspect it is just a floating point representation issue. I don't know what they are using behind the scenes.