Should I email him or wait till I know that he is interested?

There is a gentleman that comes to my work. He is so shy and I finally got him to talk to me. He normally stops in for a few minutes and then leaves. Lately we been joking about who is going to cook for who. One day he gave me his business card and it has his cell number on it along with his email. He then informed me that his cell on his card is his personal cell phone. Yet he has never asked me for my phone numbr or asked me to call him.

Some friends tell me to call him or email him. Yet since his shy and has not come forward to asking me out I feel I should wait.