No, if the course works from grunt server then the build should be fine. All that does is create a node-based webserver and serve the course on it!
When you or your colleagues are running index.html - are they doing so by just double-clicking it i.e. 'running it locally' (the browser will have file:// in the address bar)
If so, try instead putting the course on a web server then running it.
Local security restrictions will generally prevent a course from working if you just double-click index.html on your local file system.
How much is prevented from working varies from browser to browser - and what settings you have applied to the browser. Chrome won't load Adapt at all for me like this, Firefox will after a short delay (but will log a few errors in the console); IE9 doesn't work either even though I've checked 'Allow active content to run in files on my computer'.
Web content should always be run from a web server. If you run it locally it either won't work at all or it will fail in some strange way.
If you do ever need a course to run locally - say you want to put it on a CD-ROM - you'd have to package it up as an executable file using something like NW.js - which is generally quite a pain to do.