Poking around online there seem to have been some people who ordered the -50 and received the -60 in the mail -- probably the supplier just hadn't updated their website or whatever, or maybe didn't even know about the change.
I haven't found any instances of there being a big recall hullabaloo or anything. I've got about ~30k miles now on the old ones . . . haha based on a sample size of one, it's probably fine?