Just a tip; although GCC is an excellent compiler do keep in mind that Clang (for example lang/clang34) is a preferred compiler on FreeBSD these days as well. In comparison to the older GCC 4 I think you may even see a nice performance increase as well.
Thinking about it, I don't think this is a bug. The reason it's called gcc48 is that it's possible to have more than one version installed. If the software being built is from ports, the system will handle that. Unported software should try to use cc rather than gcc, or at least try it first.