The newer versions have a raised lip around the switch that older models didn't have. Time will tell if this becomes an issue with mine, I sure hope not.
Here is a link if you want to purchase more of those lights. Key Chain Light Series - MicroStream® | Streamlight
Might not be a bad idea to pick up a couple extras. I've had a couple of them given to me during the Glock Advanced Armorer Courses and they haven't been terribly reliable in my experience.
I carry an Elzetta Charlie in my back pocket.