@ Wide-O:

This actually happened to me during the summer. I had an "nervous system episode" happen to me right around the time the Olympics started (August 2012 then?) and panicked and had my serum B12 level pulled again. I thought for sure I'd be deficient. I had stopped injections and was only doing sublingual B12s 5000 mcg (methylcobalamin) for several weeks. The reading? >2000.