second 97 KK I've seen with blue decals, and the other had down tube rear mech routing. That compares to four with yellow decals, of which yours is the only one with TT routing.
Whether the blue decal was an option, or a mid-year change I couldn't tell you, but considering the variety of the examples I guess option seems more likely.
In 97 the standard Hei Hei decals were blue and the King Kahuna were yellow, but you could have them the other way round if you wanted (according to the Kona docs that the local Kona dealer of the time here has).
I have a few shots of original Hei Hei's with the blue.
I also have shots of 20" 97 Hei Hei's and KKs with top cable routing. The frame numbers either side of mine have appeared on ebay since I got mine and they also have top routing and as all three have serial number less than 20 (for the 20" 97 KK) I can only assume that the change on largest frames was done pretty early on.
Anyway its nice to see the blue on a 97 as lots of them have been removed in recent years.