Its a great offer Beth and I would accept it. You can pick out the rocks while spreading, I do that all the time.
A few stones in beds does not make a huge difference but they are wasted space compared to compost; I am often pulling gravel and stones that I see on my beds, throw them into the hedge.
Also I never sieve (love the language difference) my compost, just break it with a fork, but that is just my preference.