Gs300 Transmission Fluid Lifespan

[djspawn00]

Not too long ago I had my transmission fluid flushed and filled at my local lexus dealership. The other day I decided to change my oil and do a drain and fill on my tranny fluid. Everything went fine except I noticed my tranny fluid was as black as my engine oil... is such a drastic change in color a normal thing or signs of something else? The drain took about 2.5 quarts of dirty fluid but I immediately noticed my transmissions shifting smoother. I plan on doing a drain and fill again in a couple of days, then either another drain and fill with my next oil change or just a flush and fill instead.