How do I get a co-signer off of our mortgage?

My husband purchased our house before we were married, and since he was working in what was considered a "seasonal job" (carpentar), he required a co-signer for our mortgage. We have had our house for 6 years now and have never missed a payment at all and our co-signer has just called to say that he would like off of our mortgage. How do we go about doing this? We are in Canada, so do we need to reapply for our mortgage on our own now? My husband has since then switched careers (he is a career firefighter for the past 3.5 years) and we have a more secure income. Are we going to have a problem with this? I don't think that we will, but I'm just nervous, that's all! Thanks for your help!