I am replacing all the planking on a Thompson and all is going well so far...I think. However as I was reviewing my work so far I noticed a four inch horizontal crack in the middle of one of the new planks. At first (after cursing) I assumed I had to remove & replace the plank. However after pondering a bit more I wondered how this horizontal crack is any different than the horizontal plank edges? If a horizontal plank edge is not a structural problem why would a (tight) horizontal crack be a concern? How is this different than if I had installed two narrower planks instead of one wider plank? Vertical cracks a concern, but a tight short horizontal crack is not? Replace, repair or ignore? Maybe install some additional rib tacks as if the crack is a plank edge? Thoughts, guidance and recommendations welcomed...thanks.