Natural Weapon proficiency for Druids?

Maybe it's just a limit to dndB, but looking at the sheet, I can't help but notice there's no explicit proficiency bonus added to wild shape Natural Weapons. Are Druids _supposed_ to be proficient in them and players just need to remember to add the hit bonus manually?

If you are using the 5.5e rules, "natural weapon" is no longer a term with mechanical importance. The words can still be found in the Alter Self spell, but they just relate to Unarmed Strike.

When you wild shape into a Beast, you directly use the information and bonuses from the stat block when you use those actions to attack.

According to the rules:

Game Statistics. Your game statistics are replaced by the Beast’s stat block, but you retain your creature type; Hit Points; Hit Point Dice; Intelligence, Wisdom, and Charisma scores; class features; languages; and feats. You also retain your skill and saving throw proficiencies and use your Proficiency Bonus for them, in addition to gaining the proficiencies of the creature. If a skill or saving throw modifier in the Beast’s stat block is higher than yours, use the one in the stat block.

So your PB isn't used beyond the highlighted sentence and you don't need to recalculate any bonuses.

EDIT: too slow, ninja'd by wagnarokkr!