Wow, funny a similar thing happened to me a couple of weeks ago. I called them and they apologized profusely, but seemed a little clueless how it happened. They credited me for the overage and also all the shipping charges.
I am a big fan of Brownells and intend to keep using them, but like anything be vigilant of all charges.
A major source of objection to a free economy is precisely that it ... gives people what they want instead of what a particular group thinks they ought to want. Underlying most arguments against the free market is a lack of belief in freedom itself.
- Milton Friedman