I was cleaning my bike up and getting it ready for spring  and found a tiny groove in the upper part of my fork. It's about 4 inches long, and if I run my fingernail across it, I can barely catch it. I noticed that the seal is seeping a little, but I'm worried about the groove more than the seal, (I plan on changing them in the fall) is there a possibility that dirt might have gotten past the dust seal? Should I replace the upper before I ride?  

Is the groove vertical , horizontal or on a slant? When ya hit the brakes or go over a bump, does it pass thru the seal?
Edges cut seals. Smooth transitions dont. If a cylinder isnt perfectly round in a spot AND the rate of change over that area isnt greater than the ability of the seal to close in on, then itll hold. I sanded & filled some really ugly cuts on the backhoe rams. Thats been a coupla years & its holding.

Okay, then Id consider cleaning carefully while its taken apart. Youve got to CLEAN all the oil off then decide how to proceed. IF theres not a raised edge, but I suspect there is, then Id look at folding a piece of sandpaper, like 1,000 grit & running it in the groove, then put jb weld in it. Id mask it off very carefully & leave the JB weld standing to the height of the tape. Put a lamp on it, whatever, keep it warm,, & ya want the metal at 80 degrees or so,,let it sit a full 24 hours & then peel the tape & using 1000 grit & a spray bottle & a Very Flat, light narrow ( no more than 1/2" wide) block. No pad, just a hard, flat block, with rounded edges, so where the paper folds around doesnt create any quick turn of the paper & create a high spot because of the fold. Work at an angle across, carefully following the radius of the tube. LIGHT strokes. Watch for the paper on the chrome, tho, 1,000 grit wont create much damaging stuff for the seal, but this is a "less is more" moment. YOu can mask off just a little bit away from the JBweld & thatll help in the cause. Youre looking to run the paper up & across & down & across like you were creating a crosshatch inside a bore. Approach from both sides, going up & down & across. Id probably run the heel of my hand on the tube & work the wrist across as I went up or down,.Go slow,
If the groove is too small, it may not hold the JB in it,, Id give it a go, cuz Im just that way,, If the groove holds it anywhere & it is the same width & depth everywhere, then that tells ya ya didnt get it clean & prepped well enough in places.

Id use Berrymans brake cleaner followed by denatured alcohol on a clean, no lint cloth,..as in Tee shirt or underwear.
No alcohol? Id rub it with a clean dry cloth till my finger got hot,,
Then sand in there, then spray, then rub again.