These noises can be hard to pin down. Since the bike is pretty new the bikeshop probably has a "free tuneup" that you could take advantage of. The obvious place to start is with the crank and bottom bracket. To tighten the bottom bracket you'll have to remove the cranks. With the cranks removed check that the chainring bolts are tight. I checked all these things on my touring bike to no avail recently only to find out that it was my saddle! You see I had installed a new saddle was creaking with a high pitched click sound every time I would push down on the cranks - making it seem to be a crank problem. But, like you, when I really applied pressure on the drivetrain with my butt out of the saddle, the noise was gone. So, just as a test you might want to ride out of the saddle a little just to check if its something other than the drivetrain.
