Neither did I but at least I have an excuse. I was at Home in 1864 Philadelphia with Momma and Flag Day didn't become a holiday until June 14, 1916 when President Woodrow Wilson issued a proclamation.
Though Flag Day is not an official federal holiday, Pennsylvania became the first (and only) U.S. state to celebrate Flag Day as a state holiday on June 14, 1937.
(National Flag Day was established by an Act of Congress in August 1949.)
Here in Philadelphia, the Betsy Ross House has long been (or at least it will be) the site of Flag Day observances. The Betsy Ross House may be where Betsy Ross lived when she may have made the first American Flag.
I think I'll walk over to Betsy's house and salute the flag.