brake fluid leak

[eurotech 12]

hi all i have a 94 3.6 turbo brake lite cam on today checked fluid was down added some lite went off for about 10 mins came back on so with further inspection i found it leaking from pressure sensor on brake booster pump pulled off pump unscrewd sensor looked like rubber bits coming out of the end of sensor so i guess an o ring failed so i orderd a new sensor is there anything else that would cause this to fail ? or is this common ? car has 70/000 mi. on it and is there anything else i have to do after installing new one? thanks dave