If you have a lot of run time on your car (if it is older), I would inspect the shock shafts even closer. Most of them are made out of a stainless alloy that is quite porous. As dirt and minute dust particles fill the pores they become like little knives and cut the 'O' rings. Then you get leakage. There are two solutions. 1: new shock shafts every so often, 2: new "unobtanium" shock shafts that are an Associated aftermarket parts. They are expensive but you can go much longet between 'O' ring changes. Make sure that when you change 'O' rings that you change the oil too. The oil can hold a lot of dirt in suspension.