I always appreciate it if someone sends me a private not about a typo or grammatical error, because I make plenty. There is nothing more embarrassing than rereading something you wrote a year ago and noticing a glaring error that has been there for everyone to see. I’d much rather fix it immediately.
I do the same for others. I even sent Tim Denning a note about a typo in one of his articles, but he never responded, so probably wasn’t impressed.