The check engine light on my '93 KR Verada is on for about 15seconds upon any start-up...does this mean it needs a service? Or does it mean something else?

Does it stay on continuously from the second you turn the key, or does it initially go off and come back on again?

The normal time for the check engine light to stay on when you first turn the key is about 10 seconds, if it's REALLY cold it might take a bit longer to go off, but I wouldn't worry about it unless there's other stuff wrong with your engine.