Should I accept this?

My pool was replastered last season. Within a few months, this "feature" showed up:

http://putfile.com/pic.php?pic=4/11502092264.jpg&s=x402

The contract states that they're not responsible for visual imperfections in the plaster, as did the other contracts I got with other estimates, but this seems significant.

I'm looking for opinions on what I should do - go after the company, grin and bear it, or is there a way to treat the plaster to make this at least less noticible?

Thanks
Ken

I would say get a good service company to treat this, because thats not a plaster fault but more of a chemical fault. Once the plaster is up and you see no imperfections in the plaster its out of the plaster company's hand they have no control over these defects that you see.