OK, so, lemme get this straight... you usually only boil your first runnings, and dump the second runnings into the carboy without boiling at all. But, this time, your brew partner dumped the second runnings into the kettle, and you boiled them instead?
First of all, your brew partner did you a big favor – you want to boil (or sanitize by another method) anything that touches your beer, to keep it from getting infected.
Second of all, not surprising that you ended up with higher gravity. By boiling those second runnings, you're getting the same amount of sugar as before, but you're boiling off some of the water you would've otherwise added straight to the carboy. So, your beer is both cleaner and higher ABV – win-win!
Besides being more alcoholic, your beer will have a thicker body and probably end up sweeter. Whether this is good or bad kinda depends on style... if you turned your stout into an imperial stout, yay! If you turned your IPA into a half-assed barleywine, maybe not so great.