It seems to me that the Versed may have been mixed wrong meaning that it was diluted more than the nurse thought and that she thought you were getting 1mg the first time when you were getting much less. This would mean that when she finally gave you the entire amount that you really just then got the full 1mg amount.
If the fluid had infiltrated into the tissue around your vein it would have hurt and the nurse should have know it right away if she was watching.
The only other rexplanation is that you have become somewhat resistant to the Versed which is highly unlikely. I would make sure that you tell any other anesthesiologist about this incident so that they can watch even more closely and know that you may not respond to the medication quite like they expect.
Without being there it is not possible to give you a more definitive answer. By asking this now and being careful you are protecting yourself.
Joni I Berry, MS, PharmD
Clinical Pharmacist