Cacao Nodes Turning Red

Really not sure why this happens still. Red (named because all the leaf nodes were red from the start) I figured was just how that variety grew.  But now I'm wondering if it's how it's growing instead of what is growing.

This picture is of one of the cacao trees that traveled over to the next cubical to be cared for.  Only this last leaf so far has the distinct red nodes.  The rest of the leaves are just plain green.  Maybe a little darker at those points but certainly not a different color.

As you can see though the traveling plants are doing just fine as well.  New leaves coming in all the time and a nice color to them.  There is no gnat colony over there though so I guess that's a plus as far as worrying about them.  I've been thinking about getting this one taken care of.  They're not really bothering me but I don't want them to become an office nuisance.