What was found
AIRCRAFT WAS NOT GROUNDED: AN EMERGENCY WAS DECLARED AND THE ACFT RETURNED TO LAX DUE TO THE FLT CREW REPORTING THAT AT FL370 ABOUT 40 MINUTES INTO FLT A NR 2 ENGINE LOW OIL PRESSURE CAUTION MESSAGE DISPLAYED ON ECAM, THE OIL PRESSURE CONTINUED TO DROP ALL THE WAY TO 20PSI (RED) & STAYED THERE FOR ABOUT 3-5 MINS, BEFORE SLOWLY TRENDING BACK UP WHERE IT STAYED IN THE MID 120'S. THE FLT CREW REPORTED THAT THEY DID NOT SHUT DOWN THE ENG AS ALL OTHER INDICATIONS SEEMED NORMAL. THE AIRCRAFT LANDED SAFELY AT LAX AND TAXIED TO THE GATE UNDER ITS OWN POWER. MAINTENANCE REPLACED THE NR 2 ENGINE OIL PRESSURE PUMP AND FILTER ASSEMBLY IAW AMM 79-21-41. A SATISFACTORY LEAK & OPS CHECK WAS ACCOMPLISHED WITH NO ISSUES NOTED.