If your wife qualified for the loan on her own and title is in just her name, I believe the only document you should have to sign is a document acknowledging your wife is taking the property as Sole and Separate and, therefore, you have no interest in the property. In fact, if this is how the property was held previously, that fact has already been established and you should not have to sign anything.
I would read the document(s) they are having you sign over very carefully and make sure they are doing what you want, as opposed to what they want to have happen. In other words, make sure they are not somehow getting your guarantee on the loan, if that is not what you want.
This is best asked of a title person. Maybe there is one out there who will chime in, or if you do not get a definitive answer let me know and I will ask my title person.