Correct, that Certification is a lifetime cert. I went through a similar experience, though I was originally certified in the mid 60’s. I decided to go through the course again for several reasons. One, the technology had changed some, ie; BCD’s and Octopus regulators. Never had those things back in the "Dark Ages". Also, we learned under Navy dive tables which are different in several ways. Mainly in a 60’ pm ascent rate (follow your bubbles) as opposed to the 30’ ascent rate, based on Doppler readings. Not sure when they switched the tables around. Might check on that. We also never did safety stops at 15 feet. Some differences that may have been in effect in ’93, or not.