Can you be turned into a vampire just by offering blood?

I thought you had to ask an existing vampire to turn you but I have been playing a couplewhere the wife is a master vampire and the husband is just a mortal and she got hungry one night and asked him for a bite.  Then days later he is checking himself out in the mirror and says something seems odd.  I think he might be turning into a vampire so I need to fix that drink which will stop the transformation?