oh no, hope it is not a borer like the ones that just took out one of my chinese fringe trees! Do you have round holes that don't have a black shiny butt at the entrance? I did an autopsy on my fringe cause the roots still looked white and healthy but the tree all but dead. Found some shiny black butts, then white larvae way down in the wood and many holes.that went to the middle of branches and trunk. Some all the way thru. check out my post on the chinese fringe under general
Looks like yours are just getting started? or do you have any little round holes in other places?
I will follow this thread with interest and hope it doesnt compromise your box....dang now I have to go check out my boxes, I have several that are losing their bright green color, havent looked for holes in their knarly bark yet....