At least one other of our fellow Forum members has one like that.
The two most important rules about Smith & Wesson collecting is that:
1) Every rule will have an exception
2) Smith & Wesson wastes nothing
Smith & Wesson is a tool manufacturer, not a collectibles Company, so transitions do not always happen as cleanly as a Collector might like.
If at the time the Factory was ready to release the 3" Model of 1989, some -2 frames were found on the shelf, the Factory would have used up the -2 frames.
According to the end label, your revolver was manufactured on January 22nd of 1990.
Kind of interesting since my -2 (SKU 100921) Model of 1988 is numbered less than 2000 before yours but was manufactured almost a year earlier on February 18th of 1989