What is referred to as "tight lock up" over in the revolver section of the forum does not apply to your gun. A semi-automatic pistol can still be referred to as "tight" if there is a very close fit between the frame, slide, barrel, and bushing if present. This is more applicable to well made 1911 pistols. Few polymer guns could be considered "tight" by any stretch of the imagination, but they are not suppose to be. They have a different purpose and different tolerances in manufacture.
To check for "tightness" on your gun, close the slide, remove the magazine, and shake it. Does it rattle? Probably so, most polymer guns to. Then with the slide still closed, push down on the barrel through the ejection port. Does it move a bit? Probably so, but again it's not an issue.