I can only guess and don't want to alarm you necessarily. It seems there is some slight association with Barrett's and esophageal adenocarcinoma - I'd presume from the irritation of the acid followed by inflammation. The risk is only 0.5% per patient-year.
Seeing a doc can maybe give you some peace of mind. Maybe a little snip for a biopsy is on order. In the meantime you might ask here:
http://www.medhelp.org/forums/Cancer/show/59
But I'd guess the node is still small so I wouldn't get too worried just yet. Also, can you check above your left collarbone to see if there's anything suspicious there?