Summerstorm - that it something that irritates me too. Irrationally so.
I had a standing joke with my ex manager, who would always say "me and George went . . . " and I would immediately jump in with "George and I". It could take a very long time to tell a tale, and we'd both end up in fits of laughter.
I think there is a time and a place for correcting things, but you have to choose your time carefully. I used to correct my children's teachers' comments on homework. If they can't write correctly, how on earth were they meant to teach my children? Thankfully all my children have mastered the knack of spelling, grammar and punctuation. I think I would have had to disown them if they'd become sloppy with it!
Personally, if I had said something incorrectly, I would far rather be corrected, than to continue with the error.
(Posts, desperately hoping that there are no glaring errors in the post!!!)