Can a lawyer take his entire fee from an estate property sale before the estate closes?

The lawyer took his entire 3% fee from the sale of the first property. He and I assumed there would be no further additions or reductions to the estate, but now the second property will not sell for as much as I had originally thought, which reduces the value of probatable assets and thus the lawyers' fee. There is still another property to sell and the estate won't fully close for a few months. Is this common practice or did he jump the gun assuming there would be no further additions/reductions to the estate? Will I have to fight to get back the money he already has since it represents the entire estate which is now devalued?
Property For Sale