I forget how long the certificate is valid for before you have to get a new one. I know in my case, I had my certificate for about 6 years after I was out of active duty. When I applied for my mortgage with VA backing the loan up, the lender wanted me to get a new certificate. Needless to say, I spent a bit of time down at the local VA office getting a new, updated certificate. I thought I had to bring my DD-214 along to show proof of my service. It was actually a pretty quick process.
On my current place, I have used my VA loan. I also did a streamlined refinance through the VA a few years back. On the streamlined refi, I didn't need to get a new appraisal, survey, etc. - which saved some $$ when it came to closing costs.
Oh, yeah, Brutuskend, your certificate was issued in '75 - making you a little old. However, at least you grew up in the 60s. My certificate was issued in 1986.