Lung Nodule

I went into emergency due to shortness of breath, dizziness and a few other symptoms which I thought were heart-related (I'm female, 46 yrs of age).  All heart related tests came back negative but they did a dye induced CT scan of my chest just to be sure there was no pulminary embolism. After waiting 2 hours for test results, the ER doctor came in and told me all was normal and I was free to go.  Said it was stress-related or an anxiety attack.

5 days later my GP called me and said she received the results of my scan and the radiologist wrote on it that I had a lung nodule but not to be concerned about it.  I asked her do I NEED to be concerned and she said no, just come back in a year for a follow up appt.  She never did say what size the nodule was.  

Do you think I should be concerned about this or just let it go like she said?  I'm just wondering why the ER doctor never made mention of it before I was released.