Harvesting forrest square negative shilelds?

[forgedplayer]

Playing Civ 3 Gold Edition PTW. Was having a worker harvest a forrest square to speed production of a temple. When the forrest square was harvested the time to complete the temple went from 12 turns to 14! I thought when you harvested forrest it was supposed to give you 10 non-corrutped shields to the city production. Anyone else encounter this?

 

[boogaboo]

No bug here -
You lowered shield production for the city when you cut off the forest.
You earned 10 shields, but "killed" the forest tile..