In finishing off my 90g stand, I noticed a knot on the front top 2x4. No clue how I missed it initially! Here are pics of it from the top and from the inside of the stand. Is it unsafe? The perpendicular 2x4 in the pic is one of the horizontals which is 2/3rds of the way across so the knot is a little more than 2/3rds over from the left if facing the tank. (If that makes sense)