There are 2 types of Colt M4 handguards

[ether]

I, like alot of people, had loose hanguards on my late-2007 model 6920. I ordered another set from Specialized Armament just to have a spare, and lo-and-behold, they're differ'nt! These new ones are TIGHT, and they're relatively smooth vs. textured, which the loose original ones are. These "new" ones are also more reminiscent of the smoother/harder (and probably more heat resistant, though more brittle) standard carbine hanguards I'm used to seeing on the 6721 and 6520. So I guess loose 6920 handguards are only "normal" if you have the loose, textured variety. Frankly, I doubt there are any issues with the "loose" ones, but I do like these that fit snuggly much more.

ETA: I don't think these "new" ones are new at all, but the opposite. I think the textured loose ones are a newer development, and maybe just for the LE M4 carbines.

[Robb Jensen]

Probably made by a different vendor for Colt.
IIRC Colt doesn't make their own handguards, stocks nor pistol grips.

[ether]

I have no idea, but their furniture (handguards, pistol grips, and telestocks) have always been pretty distinct and easy to pick out of a crowd. For instance, their handguards traditionally been made from a more smooth/hard/brittle thermoplastic. They're the only company that uses the grey, fuzzy pistol grips...which I really wouldn't prefer normally, but there's nothing like a brand new Colt with a fresh, dry, "fuzzy" grey pistol grip. And they used to be the only maker that used the new generation "sharp right-angled" tele-buttstock, but now S&W appears to be using them...or something very much like them.