Does the sheath on your Crotalus have divots in the mouth of it? If it just looks rectangular (which I'm guessing it does) then it was one of the first run, which had some sheath fit/retention issues. If that's the case Condor would hook you up with one of the revamped sheaths, I'm sure.
Here are some pics of the sheath. Let me know if this looks like the first gen to you.

