I recently moved into a brand new house and noticed a crack extending the full width of the driveway right where it meets the perpendicular sidewalk at the street. While clearly the crack was not man-made, it was fairly straight all the way accross with a bit of a jagged edge about it. I asked the builder's sales agent about it during my pre-settlement inspection, and he said he thinks there is "felt" under that crack. I took that to mean an expansion joint is under that crack, but why would it be covered up! At any rate, two months later, I'm seeing bits of concrete popping up / cracking up over top of and on both sides of that crack exposing what looks to be a cork or felt expansion joint material. It appears that this material was perhaps burried 1/8" or so beneath the troweled surface. I looked around the neighborhood at several of the other new construction homes and many (not all) seem to have the concrete trowed right over that material as well; leaving an ugly cracked up joint with some exposed black cork (expansion material) coming through underneah. I was hoping a member of this forum could shed some expertise on what I'm witnessing with this crack, and will everything be OK with it- meaning, should I just not worry about it and let the concrete natually do whatever it is going to do there? Thank you in advance!