Improve can't gunzip content error

While trying to validate http://www.mdsupplies.com the following error is
show:

A fatal error occurred when attempting to decode response body from
http://www.mdsupplies.com/. Either we do not support the content encoding
specified ("gzip"), or an error occurred while decoding it.

The error was: Can't gunzip content: Header Error: Minimum header size is
10 bytes

The same page can be validated by the Nu validator with no errors. It can
also be fetched by google and displays correctly in all browsers. If this
error could show the request/response headers it would be very useful. Or
if it could list the actual specification(s) that the response is violating.

Thanks,
Joe