It's just a baby, give it a little time. If the new leaves are bigger, that's a good sign. Are you giving it lots of sun (acclimating gradually so you don't burn the leaves)?

I started with a small eBay plant. Got up to about 3 feet the first year, about 8 to 12 feet in subsequent years. Hang in there.

Thanks for the response. I was really starting to worry. It's been in full sun for about the last 3 weeks and the new leaves are nice and green, and like I said, getting pretty big. It's also in a container, so that might be part of the reason it's not going gang-busters. Thanks again for the re-assurance.

Billy

Billy, you're welcome. They do grow more slowly in containers than in the ground, in my limited experience.

It's getting kind of late in the season to disrupt it again, but you really should have put a basjoo right into the ground. Then you would have seen more growth.
Give it a water soluble fertilizer with every other watering, let it dry slightly between waterings, keep an eye on it for spider mites, aphids and japanese beetles. Depending on where you live, full sun is sometimes too strong for a container plant.