Excellent suggestion. I also often take the seatpost off and turn the bike upside down to make sure any water I might have picked up while riding in the rain drains out. Give it some side to side shaking while tilting it too so that any water trapped in other parts of the frame has a chance to make it out. Sometimes water will run down through the top of the seatpost when riding or in my case, it will hit the flat area of the stress-relief section of my carbon post and run down into the seat-tube.