Well, my advise is this: The code original code is taken from here. If you take a better look into that repository, you'll find out that there is actually a LICENSE file there. It has some conditions (it's BSD license) that should be easy to meet. As far as I can find there is no exception for examples so they are under the same license. So, if the conditions in that file are followed, then there is no problem. Whether you'll need to copy that LICENSE file's copyright notices or not, depends on whether you'll redistribute it.
Open Source allows code reuse and studying of code. Therefore you can always look into the code and learn new tricks. For personal use you don't need to care much about the license even if the code is used in another work (program), just when you redistribute some consideration is needed.
I think you should include those copyright notices, unless the copyright holder of the original code has given you permission to distribute that code without them (for example if there is a text that examples can be used freely, no rights reserved). Anyway, as far as I know the easiest here would be to include a compatible license with needed copyright marks with the code. When I say compatible, I mean a license that has at least the same restrictions as the original, i.e. it doesn't have to be BSD.
Anyway I don't have a problem. It's between you and the copyright holder, whoever that is.
With my message above I wanted to remind that although with Arduboy things are usually Open Source, we can not assume that everything Arduboy related is automatically Open Source. Therefore it's important that, when you release something, some kind of permission to use (and modify, redistribute) is given. The best is to use an Open Source license.