Can you help me solve a mystery?

[michigan.watches]

I'm going through my inventory and I discovered an oddity with a Rolex warranty paper. The papers don't show the serial number of the watch (or any other watch) and there is no area to fill in the purchase information. There is a number after the model number but it's one character too short to be a serial number. The printed date on the bottom right corner is 1989 and the watch is an L serial. Can anyone shed some light on this? Thanks!