Change trans oil and brake fluid at 19K?

[desert]

I have a 2004 E320 wagon with only 19K miles on it. I took it into Mercedes for a cargo cover problem ( it WAS the rear SAM) and I get an E-mail from them saying they had checked a number of things ( without my direction) and that my trans oil and brake fluid were "dirty" and needed flushing etc. at cost of approx $600. I've never heard of flushing and changing fluids at 19K especially on a car that is driven very lightly.
Does anyone think what they are saying is necessary or just a come on?