Yea, I've broken spacers by tightening too much. Just so happened to be drive side, as well. Paranoid that the wheel would slip under too much pressure, I guess.
Just maybe you didn't tighten the chainring bolts enough, too tired from cranking down on the hubnuts
.
Or, they had too much grease on them (or none at all), or your hands had too much grease and couldn't grip the allen key and the crappy parktool chainring bolt tool.