Yeah give the fork tube a good look over. Rock nicks will cause weepage and seal by pass. Even something that adheres to the tube and dries hard could damge the seal and evidence be washed off later.
Personally a mild film I'd live with, the alternative is disassembly and replace the seal.
Removal of wheel and brake caliper, remove tube cap while still clamped in trees, watch for spring to pop out as threads disengage, pull out spring and spring spacer, removal of slider to damper screw through access hole in center bottom side of slider, slide chrome wiper retainer and rubber wiper up and off the top of the slider, remove seal retainer ring, then using the slider as it's own slide hammer slide slider up to fully compressed position on tube and rapid pull down, it may take more than once but the lower tube bearing will pull the seal out of the slider top and the slider will come off.
Replace the bearing from the tube bottom while you're at it and put all together in reverse order, add appropriate amount of oil, put spring and spcer back in and compress the crap out of it while trying to start the cap threads and not cross threading it.
Lot's of fun.