Just curious? When you put your choke into your gun, did you just screw it in dry or did you lube it? If you just screwed it in without any lube it will seize up as you shoot it and you won't get it backout. The same goes for putting just an oil on it (like 3n1 oil) as you shoot your gun the oil will lock the threads of the choke up, yes it will lube the threads up and screw in easy and keep it from rusting, but in the long run will do more damage to your choke. Use a good Choke Tube Lube and don't put to much on, just a little is all you need, put some on and screw the choke in and out a few times, then wipe the threads on the choke off and put it back in, it won't effect the tube any and you'll be able to unscrew it easially. That is a must on any new gum you get. When I bought my new gun I didn't take the choke out and lube it, I just shot it and left it in the way it came from the factor. After season I went to clean my new gun up and store it until next season. I couldn't get the choke out, It took two guys to get i out, I held the gun and we wrapped leather around the choke and used a water pump pliers on it to break it loose. Hard Lessen learned. Since then I've lubed it and it goes in and out with fingers.
It could of also been the threads on the choke weren't as clean when cut as they should of been? Remember everything is human made, so there is always a chance for a little error.