How flat should the top of a new acoustic guitar be just below the bridge? Meaning, if I lay a straight-edge across the guitar from one side to the other, just below the bridge, and from that point to the bottom edge of the guitar, how flat should it be when new? I picked up a Martin D-16GT last night, and if I lay a 12" straight-edge across the guitar as described, there is a gap on either side of the straight-edge. I can rock the SE from side to side and near the bridge, there's almost 1/4" of room under the SE when rocked to one side. The top doesn't appear completely flat till you get as close as 2" from the bottom edge. Help, should I take it back?