I’ve only ever heard that from Americans and it’s always puzzled me.
Yes, but then they do quite like using "of" superfluously, it's a common tic. They might "get off of" something rather than just getting off something.
What puzzles me the most with our American cousins is use of "I could care less".
Argh! Surely if you want to illustrate that you really don't care about something, it can only be "I could
not care less". That places you on the scale of caring right at the lowest end. Excellent, it's now very clear that it's impossible for you to care any less!
Now, if you
could care less, that means that your level of caring is somewhere along the scale, that you at least care to some degree. It's even possible that you might care an awful lot! What it
can't possibly illustrate is that you don't care, which is precisely what you're trying to convey.
(I love you really Americans, but that one thing fries my brain. You can probably tell that).