Simple mistake simple apology, not that big a deal imo.
Small tangent, what gets me though is a number of companies don't seem to take their social media feed very serious - or at the very least, they don't copy edit it or proof read, or even have someone glance at it before it goes live. It's kind of funny to me in company cultures where press releases or any ad campaigns have to be vetted and double checked, the young kid that gets assigned the social media account can say whatever they want with a few clicks.
We have a small local tv station - fairly decent station for a smaller market, but wow the person that they let run their facebook page comes across as 16. Every story is prefaced with a usually inappropriatly excited sentence or two with tons of exclamation points. Like "Incredible accident on xxx roady!!!! Fatalaties! Stay away!!" Does no one at the station ever bother to look at their own social media?