My guess -- the "good" redirect (without port number 80) is coming from GlassFish web container whereas the "bad" redirect (with port number 80) is coming from GlassFish Grizzly (low level network io library for GlassFish).
As you might be aware, GlassFish loads containers on demand. If you have no web applications deployed then web container is not loaded and all traffic is handled by grizzly component of GlassFish. When you access admin console, which happens to be a web application, web container gets loaded and grizzly sends all HTTP traffic to web container for handling resulting in a different behavior.
A workaround will be to have a web application deployed. Once GlassFish sees a user deployed web application, it will load web container during startup and therefore your end users will not see the issue.
Please file an issue on glassfish issue tracker (link below) under grizzly-kernel sub-component and someone will look at the issue. Given that there is an easy workaround, this should be a low priority issue.
https://glassfish.dev.java.net/servlets/ProjectIssues
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