Had a buddy who ran a flooring crew do the same kind of check on his own place, and he found the seams over the concrete slab were the ones splitting. Something about how the carpet pad shifts under the heavy traffic spots, he said. His hallway seam popped twice in the same place, right where folks turned the corner into the kitchen. When he pulled it up, the tape was still stuck to the pad but not the backing. Cheap tape was his guess.