It seems pretty insignificant, but it's really one of the few things that's actually irked me while playing. My brother and I duo a large majority of our play time together and like to dye our armor the same color so we feel a bit more like a team.
"Unfortunately" gear gets changed out so quickly and has some pretty bold accent colors that sometimes I'm unsure if I've dyed a piece of gear or not.
I would love to see an addition to the tooltip that points out what an item is currently dyed. Obviously it's not game-breaking, considering I wasn't able to find even one other post relating to this, but I wouldn't mind seeing that in a future patch.