I picked up two healthy, small Cannova cannas a few weeks ago and they have been flourishing, but the new growth on my yellow one is lime green,

even the flower spike started out dark but suddenly turns lime. The pink one maintained the dark green new growth and it's in the same spot, same growing conditions. It looks very healthy, not an inkling of lighter color on any other leaf. I've examined it very closely and don't see any signs of virus. Any idea what it could be?