Just bought a '05 Bonne and noticed the recovery container being dirty on the inside. Only have 30k miles on it. Any reason for it being dirty?

I can't see what kind of stuff you're seeing that looks like dirt. If it'* a simple brownish film that is probably the sealer that GM put into the motor at the factory or in some cases it was put in as a part of a recall in which they changed mount bolts on the throttle body and added the pellets with the sealer. They're made of an organic material ground finely, such as walnut shells--I can't remember the main material. In earlier models they didn't put in the sealer and recalled the cars and did it.

If it'* a sludgey, oily looking materal, it can be contaminated DexCool. Even though DexCool was said to last for 5 years or 100000+ miles, it should be changed at 2-3 years or 36000 miles just like the green stuff. Some will say remove the DexCool but it'* best for the aluminum components. The formula was changed slightly after earlier cars in 1999 or so developed seeps around UIM seals allegedly because the seal material changed due to a preservative in original DexCool formula. I use DexCool in both of mine.

You can disconnect the hose from the reservoir, remove either 1 or two small bolts holding it and then wash it with detergent and a bottle brush or anything to clean off the interior sides. Add 50/50 DexCool and you're back in business with a clean-looking bottle.

a new coolant bottle is only $12 from the dealer...

I take mine off every year and clean in out.
Since it is the high point in the system, it will collect all the crud.