Etching in Prestige pressure cooker

I purchased 12-Ltr Prestige Pressure cooker from VCT Electronics Amazon Marketplace on Nov of 2010. Cooker has not been used more than 10 times and has developed "etches". This is aluminum cooker.

Outer surface of vessel and lid(both inside and outside) are shiny and look perfect.

Etched inner surface (bad subject for MACRO photography)

Too late to claim damage in 2010 TAX.