Bow on basement drywall

I am going through a strange issue and trying to make sense of this. We are renovating an old 1980 duplex. The house on one side had a concrete patio/driveway that was sloping toward the house. First thing we did when we bought it we demoed the concrete to the gravel. now waiting on new concrete to be placed and graded properly. Getting new gutters as well.


All basement drywall are straight except for the one bedroom wall. This bedroom wall was the one opposite the concrete outside. The one wall has a noticeable bow in the middle and seems to be filled with drywall filler. It's about 1/4 inch out only in the middle. The rest of the wall in the basement is ok.

We thought this would indicate moisture and mold. We took a small piece of drywall cut with lots of joint compound on top and found the poly and insulation in very good shape.


The puzzling part is that even though we are fixing the grading and concrete outside so the moisture problem should solve it self but why the bow? Old construction? Should take down that portion of drywall fix it with new or just have the guy sand that area of drywall further to make it straight? The weird part is that the PO must have put the joint compound 8-10 years back or more as the wall paint is super old but there is no sign of cracks.


Also it rained heavily last week with floods across the city and no sign of water coming down from this wall either.