I for one don't think you over-reacted at all. My choice of words may not have been the same but you never know in the heat of the moment. Your response was a gut-check instinctual reaction which is a good thing. You NEVER know what someone's intention is and all you can do is anticipate and/or react! REaction (after the fact) can wind up with you hurt or dead. You may be incorrect in your threat assessment of the danger either way but I'd rather be wrong and alive than apathetic and dead! Isn't this why we carry?...anticipating that a threat may happen at any moment? When a threat presents itself, are you going to have a crisis of conscience at that moment?
Myop is 110% absolutely correct on Cabelas not being a safe enviroment regarding firearms! For example, they sell Mosins there that are accessible to EVERYONE! Four aisles down on an endcap they had about 2,000 rounds of 7.62x54r ammo on an end cap. Takes about 5 seconds to load the magazine and chamber a round... less if you only load 1 round per shot! What's stopping anyone from picking up a box or two of ammo and walking over to the rack of long guns?