A small amount of weepage, in the form of a very thin ring around the shaft is normal. If it is leaving oil on the bumper, or it is running down the shaft, then you need to get it serviced. Just wipe the ring off and call it good. Sometimes you will get some oil migration out of the spanner holes on the side of the seal head nut.
I too wash my bike after every ride, my rides being at least 4 hours long and 60 to 100 miles. I use compressed air to remove excess water after washing, and I wipe down the fork tubes and shock shaft with a soft rag to remove any water to avoid hard water spotting on the tubes and shaft to prevent undue wear on the seals. It doesn't take long, and it will go a long way towards extending the life of your seals.
I would not spray chain lube or anyother lubricant on the shock shaft as any residue will end up under the seal head nut and build up around the seal. Dirt will then stick to it and your outer dust seal will then start to deteriorate, then dirt will get to the oil seal.
The reason you don't see many posts on this issue is because the seals in the modern mono shock are pretty darn good and rarely fail. they do, just not that often. It is more likely that riding in wet muddy conditions will cause the fork seals to go well before the shock seal.
You should service your shock about every 30 to 40 hours max. If the oil inside the shock looses it lubricating qualities then your internal components like the piston rings, and bushing will start to wear prematurely and then it will be expensive.
