Chances are you have tried this already but, just in case ..... turn the machine off (you probably have already done that by now). Now turn it on again, and see if it mysteriously disappears. Sometimes that is all it takes.
Otherwise, take out the bobbin and the spool, and be sure to give it a full cleaning, taking out any loose threads and/or lint and add a drop of oil. Re-thread top and bottom. Then turn off for a few minutes and try again.
No sense fretting over it now .... just take it in the morning and see what they say.
Unless they have a techie there on site, chances are you will not learn much tomorrow.
(At my dealer, the techie does not work Saturdays.)
At the least, you know it is in the queue for Monday.
Good Luck!