My first thought was that this is reaction to being shipped from southern California to Maine in the dead of winter. Who knows what kind of conditions it experienced while in transit. Chinese Elms are pretty resilient and even if the current crop of leaves drop there is an excellent chance that it will recover.
Take care not to water too frequently as a tree with compromised foliage will not be using as much water than a similar specimen that is in good condition.
Read this for tips on proper watering:
I put it in my room
What kind of lighting are you providing this tree? A Southern window is best, lacking that East or West is second best and North the least appropriate. Some supplemental lighting would really be helpful if your lighting is not good.