Well, they did an MRI of my brain and they didn’t find anything. Explains my thoughtlessness, I suppose.
Actually, the meat of the report is:
1. No evidence of intracranial metastases.
2. No MRI correlate for the left frontal lobe lesion suspected on CT neck, suggesting that this was artifactual.
So, on the plus side, complete false alarm. On the down side, I have no excuse for my behavior.