How to smooth a wooden rolling pin
Woodworker and cook here. Here's something that might work (without having seen the actual problem). You'll need some 220, 320 &amp; 400 sandpaper,  alcohol and shellac (which is food safe).  Create a small amount of thinned shellac by mixing it with the alcohol. Next use the alcohol to raise the grain in the affected area. It'll create little nibs that'll stick above the surface of the rolling pin. Use a thin coat of the shellac to 'freeze' the nibs and sand lightly to remove them and the shellac. Start with the 220, lightly sanding and work up to the 400 after the shellac has dried (it's  fast). You may have to repeat this a couple of times. Keep going until you can't feel the problem area any longer.

It might be easier to just buy a new one,  but things are always better when you've got some sweat equity in them. Plus now you've got a story.