No Contract with Judges?

Hi,


Since FH and I are Agnostic, at our wedding ceremony we will be having a Judge doing our ceremony.
I contacted the one recommeded by my reception hall, and spoke to him about officiating our ceremony.
He told me that he has reserved it in his book, but that there is no contract. I feel a little weird
about this. (He just told me to give him the payment the day of the wedding.)
I mean, I know he's a judge and all, but how do I know that he's going to show up?

Do other officiants write contracts? Should I write a contract for him to sign? How should I do this
without offending him.

Opinions?

Thanks...