Timooooooo
What color did you use on your letters? Some of the dyes will wash when NeatLac is applied. For me, when I dye my lettering, I use dark brown or chocolate. I have noticed that even med brown washes a bit and I've gotten uneven shades. I dye my lettering and background, oil [let set for 8 hrs] then NeatLac. I let it set till the next day. I'm with Ross, if you have any wash at this point, you can re-apply your dye [sparingly]. Then I antique then apply TanKote. I'm done then. You may want to try different colors and applying NeatLac on some scrap leather.
Nice piece
Happy tooling
Tim