I was changing lens earlier today why talking to some people. As one of them was leaving, I naturally waved good bye to them with my 35L in my hands and I noticed that something seems like it is loose inside. It wasn't a rattle, but rather like something was slightly loose inside. As I shook it again, I confirmed that something is just slightly loose and shifting around inside the lens. I know I should just not shake the lens, but i'm curious if this is normal? could someone check their 35L to see if does the same? Thanks!