I already filed my 2017 taxes, but just received a W2 from a company that I was only employed with for a week in January of 2017. Do I need to re-file?

hello - you need to wait that the return you filed is processed and then file an amended return - TT will assist you in preparing it

Thank you for the quick response! My return was accepted and I'm awaiting the refund now. Is it too late for an amendment?

It is not too late to amend your return, with no consequence to you - but you need to wait that the return you filed is accepted and the processing completed so as not to hit it while in limbo - safer that way