I left a 2'x2' section exposed 1/4" backerboard under kitchen sink not covered with drywall around the pex and pipe area. During install it got a little wet. A week later it is still ever so slightly damp. Does this mean I have a leak in the pex elbow inside the wall? The house windows and doors were closed. The kitchen cabinet was closed. So circulation and access to fresh air was not all there. I have a tenant moving in soon. Should I worry about this or does backerboard take a long time to dry?