Our 330 is now over 150k on the clock. We went to Europe and did 2.5k miles (probably over). Burned half a liter of oil. Is that pointing at a larger problem?
Manufacturers often quote 1l/1,000mi as being acceptable oil consumption. I certainly wouldn't worry about 1/2l in 2,500mi. I suspect that's roughly what my e91 330i gets through.