Quattro Is God

The other day when I was driving my '87 5000 S, my brake pressure warning light kept coming on but i didnt feel anything in the brakes. However, the steering wheel was getting quite hard to turn. When i got home i poped open the hood to see what was wrong. The was an obvious leak of fluid around the rack and pinion, but the hydraulic reservoir was still full. I tried to find a leak of hyraulic fluid around the rack and pinion area but i couldnt find it. Today when i drove it, the warning light never came back and steering seemed normal, but that leak is still there, but the reservoir is still full. Anyone have an idea of what the hell is going on?? Thanks...