I see what you are saying about lining up now. I’m thinking they are double wide panels but I’m not sure.
As for “give”, we’re not talking a lot. But you should be able to “slide” the panels back and forth a little (with some effort). If you can’t, then the nails are too tight. And no, they don’t unlock unless there are very high winds, and then you’ve got other issues. Of course with the picture, I can’t tell how “loose” they are. The nail head should be nailed in far enough that the underside is holding the siding next to the sheeting without pinching or dimpling.
No web site, just installation instructions from the local big box store, when I was considering it for my own home.