Hi Russell,
I was unable to reproduce your issue while following the Quickstart for Go App Engine tutorial and using the Hello World sample app that was provided with it. I understand your Go app is more complicated to deploy than mine. Therefore, if you believe that it is a bug, you may want to submit a detailed defect report (with label “Language-Go”) on the Google App Engine public issue tracker and have someone look into it in more details.
Alternatively, you could also make a post of your issue on Stack Overflow which we regularly monitor as other types of stack exchange services and which would increase your chances to get a faster answer due to its larger audience.