If you have room inside then by all means, let it keep growing, even if it is a cold hardy type(M.basjoo), you'll get a jump start for next spring.
The people at the nursery may have been telling you to divide the pups from the mother so you'll have a better chance at getting it to fruit in a large pot.

Go to winterizing bananas-Illinois. It tells you exactly what to do with your dwarf as I have one too, except mine is on it's 17th leaf. But I plan to listen to them. My nursery told me to leave it outside, the banana tree would die along with the pups. they never mentioned covering up, just leave it out in the open. The Carolinas can get frigid, as last year it went down to 11 degrees. Read what these growers say and follow their instructions.

Thank you for the help.

tropicallvr--While I love the idea of getting a jumpstart on spring, I really don't have room to keep it in the sunny spot it is in now. I am afraid the leaves will get broken et c. My only spot is the unheated garage.

cponak--I have posted a question to the winterizing banans-Illinois thread.

Here is a link that might be useful: my blog