Yeah, chainring seems a little excessive, but maybe not... new england weather is really hard on bikes, and with all the sand they used on the roads over the winter, a lot of bikes need that type of work, even bikes that haven't been ridden that long.
As for "a few thousand miles", that's really a long time for a cheaper shimano chain. With regular degreasing and proper lube, it's doable, but if you road 200 miles on a bad chain, then the cassette is probably shot, so the diagnosis seems reasonable. As mentioned above, the more often you check for chain wear, the quicker you detect it and the more of the drivetrain you can save.