A magazine sticking in not uncommon, particularly in a new pistol. More than likely the magazine that sticks is just ever so slightly larger than the other one. With time and wear this magazine will fall out just as easily as the other magazine.
If you would like to see how the fit is do the following.
1. Insert the magazine into the pistol slowly until you feel it touch the magazine release. Back it out slightly, then let it go. Does it fall free, or does it stick? Did it drag at all when you inserted it? If it falls free, then the issue is how it rubs against the mag release, and this will wear down fairly quickly.
2. Go to the maintenance section and look up how to remove the magazine release. It is really easy and all you need is a small flat tip screwdriver. Remove the mag release and repeat 1 above inserting the magazine all the way. If the magazine falls free then the issue really was the mag release and as note above will wear in fairly quickly. If the magazine still sticks, or drags on insertion, then the magazine might be a little wide. Though this also usually wears in fairly quickly, and cleaning the magazine and the mag well in the pistol might help. Also, After a few range sessions if you see marks where the magazine drags inside the pistol, a few light strokes on the magazine with some fine sandpaper may do the trick. Just be sure to disassemble and clean the magazine if you do this.
If on the other hand there is some difficulty inserting the magazine, or removing it, particularly with the mag release removed, the magazine is probably really wide for this pistol. This would be a case of tollerance stack where the magazine well is machined to the minimum tollerance and the magazine is made to the maximum tollerance. This is not too common, but it does happen. In this case replacing the magazine, or dedicating it to another 1911 (there is always another 1911) is probably a good idea.
