Is $100 to cut out defect in carpet a fair price?

I picked out carpet and scheduled installation with the carpet company. Two days before installation, they called to say there’s an imperfection in the carpet. It looks like a line in it. They said to cut that out of the carpet, it would cost me an additional $100. I don’t understand why I need to pay because the carpet is defective. Is this normal? They said I could come in and pick out a different carpet but this carpet was on sale. I get the feeling that they don’t want to sell it to me at that price anymore. Thanks everyone for your responses. I’m going to cancel the install and go somewhere else for my carpet. I smelled bs too - thanks for confirming!