Rattle from tapping molding over wheel wells?

tonight when I got out of my truck, I was looking at my bed cover and then I just for some reason tapped my hand on the molding that goes over the rear wheel wells and up to the side of the bed. There's like a rattle and I can see it's that molding, but not that it's loose on the side of the truck, I looked at it and tapped on it gently. I see that if I tap on it on the side, that underneath the bed/above the rear tire, the molding is all one piece and it just rattles against the bed. There's 2 clips that hold it if I look above the tire, but that's it. Is this normal? I don't think I've ever noticed it before and I take good care of the truck, I'm not sure now as I think I would have noticed it before.

 

I apologize for the vague details, but I think it's part 15 on this diagram I put the link to below. in this diagram it doesn't show the piece that I was referring to on the side of the bed that goes over the wheel well, but it's that plastic molding that sticks out a bit on the side. When I tap on that it makes this "wheelhouse liner" move a bit. It's not falling off, it just rattles and I want to find out if that's normal or if something happened....I don't see any clips missing.

https://www.worldoemparts.com/world...hY29tYSZ5PTIwMTMmdD1iYXNlJmU9NC0wbC12Ni1nYXM=

 

mine has always done it on both sides. I think it's been talked about here before and is normal. Not sure what exactly does the rattling, though.

 

Thanks, I think it's the plastic clips that hold the well piece on, I pushed mine up a little as they seem to loosen up a bit and that made a big difference. I'm going to just get a couple new clips because I have to get it fixed since someone hit it when it was parked...