Cam112549 - yeah, dropbox seems to be having trouble right now.
Doesn't 8 direction already take care of mirroring? I don't think you have to manually do that...
There could be a number of things going on: if your code checks for the right arrow first, then the left arrow, then if both keys are down, the left arrow will be processed last, so your sprite will end up mirrored. So, checking left first may improve things - but then you would have the same issue going the other direction.
when your sprite is moving right, its 8direction.vectorX will be poitive. So you could set your sprite to mirrored only when both the left arrow is down and the 8direction.vectorX is negative. That way pressing left arrow to stop the motion wont make your sprite mirrored until it actually starts moving to the left.