I appreciate your intent, but to wish someone "Happy" greetings in regard to Memorial Day is bad form. My dad told me, when I was much younger how the Old-Timers, including him, find that very extremely offensive and insulting.
Happy is rude to say, when referring to the dead who gave the ultimate sacrifice. Next year, please try to be more thoughtful. Try something more appropriate, like, "Remember Memorial Day," to show the appropriate respect that is due. Even "Have a safe Memorial Day," would be better.
Thank you for your attention.
God Bless the USA!
Wisdom and courage to our brave men and women in service and confusion and defeat to all our enemies.