It isn't clear exactly how you created your buffers from your question, but my guess is that you're trying to use attributes of the PointGeometry representation and using the buffer function included with that representation. By default, that buffer function is limited to buffering in the same units as the input data, which in your case with unprojected geographic data, doesn't make sense -- a unit of degree varies with both latitude and longitude.
The easiest thing to do is to use the Buffer tool, which takes a linear unit for the parameter
buffer_distance_or_field, and will automatically create geodesic buffers if passed in miles:
arcpy.Buffer_analysis("input_points", "C:/workspace/points_buffered_10mi.shp", "10 Miles")
Here's the set of linear units buffer will understand:
'Centimeters', 'Decimal degrees', 'Decimeters', 'Feet', 'Inches', 'Kilometers', 'Meters', 'Miles', 'Millimeters', 'Nautical Miles', 'Yards'