[Trev]

If the mating services aren't perfectly flat, they might have tried to seal it up like that. Not the proper way, but it's a quick fix to sell.

 

[Trev]

Are you looking to remove the dowel? If so, find a drill bit that fits the inner diameter of the dowels snuggly. Then take a pliers and carefully remove it. The drill bit makes it so you don't crush the dowel. Make sure you use the smooth end that goes into the drill chuck, not the drill bit itself if that makes sense.