Bingo, that slight residue is just the beginning. If possible ask around local for anyone that got their work done and try to find a cheaper/but good place.Yes, your seals are starting to leak. They may go for some time before getting worse, or they may go bad quickly. No way to tell. Cleaning them every time you ride should help, as the oil will attract dirt increasing the issue. Fresh seals should not leave any residue. At most, you might see a slight ring of dirt from the wiper.
Parts are pretty cheap if you do it yourself. Some shops charge $300 or more(which is a rip off). You might consider a custom revalve with replacement of the internals and fresh springs for about $600.
I used MD Racing when I had my forks done. Very happy with their work.
OEM seals are as good as any, and better than most.