My flex menu is showing the "Home" item as a parent (it has no children) and giving it the down-arrow on initial display. Once another item becomes active, the arrow goes away. I found that line 243 of s5_flex_menu.css had the following selector:
#s5_nav li.mainParentBtn.mainMenuParentBtnFocused a, #s5_nav li.active a{
I changed it to read:
#s5_nav li.mainParentBtn.mainMenuParentBtnFocused a {
The menu now seems to work fine.