Wrong minimum bounding circle in UTM

I have found Minimum bounding circles for some polygon features.Most often I find that some features lying outside the resulting circle.
Is this a bug in ESRI ArcGIS?


I used an alternative method of finding bounding circle...Find the envelope>Get the centroid>Get the farthest vertex from centroid and use ICircularArc interface to draw circle.This seems to provide correct result.

Any suggestions?