I'm working off of memory here so you may be right.
I used to collect magazine articles about the USP and thought I saw a rail change mentioned in one of them. I no longer have those articles.
My personal USP dates back to 1998 and I know the series underwent some changes since then.
Regardless, it is a very robust and reliable firearm. I can only remember 1 failure to feed from a magazine with a tired spring.
I really cannot complain about the USP.