We are having a contractor build a four season porch on the back of our split level home. He used three 8 x 8 support beams to support the wall furthest from the house. The beams are 6 feet tall and we have noticed cracks running vertically on two of the supports. The seem to be about 1/4 to 1/2 inches deep. Is this normal or should we be worried? We live in Minnesota.