Do printing vendors usually charge for proofs?

I'm having 1000 presentation folders printed and after 2 rounds of proofs (due to some small changes in the graphics), the printer wants to charge for additional rounds of proofs. I've ever had a printer charge for proofs. Is this normal? I just started using this company, and their prices are different due to 'the economy' and they now no longer have the paper originally requested to duplicate our current collateral. Opinions?