I agree with Timberland, it's not from the hair being longer. There are a few different reasons that this may happen. The hair may not be laying in the correct pattern that it originally was. I would put hair gel on the spot and brush it down a little with and old toothbrush and then I would staple some drywall sanding screen ( you can get it most anywhere) over the bad spot until it drys. This holds the hair down and also lets air through to let it dry.