Jewish people believe that you should not shake hands with the opposite sex they find it disrespectful mostly Orthodox Jews believe this, it is their religious beliefs that you do not shake hands with the opposite sex. They can not touch anyone of the opposite sex unless they are married to them or related to them such as a son or daughter, father or mother or grandparents and they can not shake hands with anyone who is not their spouse. It's a show of respect if you can believe that but many people who do not understand the Orthodox Jewish religion view it as disrespectful especially when greeting someone but we have to respect their religious views and the fact that this goes against their beliefs and that they don't mean it to be mean to anyone. It originated from the Toran and it's like a Christians bible but it's the Hebrew bible. "The word "torah" means "teaching," "instruction," "scribe", or "law" in Hebrew" (Wikipedia.com) The Torah has very strict guidelines and Jewish people follow those strict rules and this is one of the rules of the religion which is called Negiah and this means literal touch in Hebrew. Halacha forbids physical touching of anyone from the opposite touch that is not their wife or husband, children, parent or grandparents. This was taken from Leviticus it was a sin to approach anyone of the opposite sex in this way and could result in death. I hope this has helped you to understand better why she could not shake your hand and you shouldn't take offense to it. If you need more help or information let me know.