[Cthulhu_]

I've only dabbled myself, but I can see how that would start; I come from a Java background which forces you to have one module / class per file, but Go doesn't. It's very easy to start hacking up a thing, and it's easier in development to just keep it in one file. Of course, the nature of code is that it grows, so spend enough time there and it'll start growing. If you're familiar with the code (as in, you wrote it yourself), single files shouldn't be a problem.

It's not uncommon in other projects either, NodeJS for example has a relatively small number of large files (https://github.com/nodejs/node/blob/master/src/node.cc).