Actually, we missed it (I was wondering why my wife has not been talking to me -- was I supposed to buy her some chocolates or maybe a Greek grammar?). The The International Organization for Septuagint and Cognate Studies has declared February 8th International Septuagint Day. Apparently, they had a team of eight scholars sit in individual vestibules for two days and think about what day they would celebrate the LXX. All eight were inspired to choose the eight day of the second month. Amazing! In truth, this story is somewhat apocryphal. The real history of the origins of the so-called International Septuagint Day are lost to us, so I have made up this handy legend which I hope others will inflate to suit their own theological agendas.
TW: In an excellent post Tyler Williams, who didn't miss it, gives his reasons to study the LXX, here.