I have seen the same thing only occasionally with my LEFT rear door lock. Not recently though. Will wait until it gets worse. I noticed by using the keypad to lock all doors rather than noticing it with the fob. You can hear the actuator but it's just not pulling the lock down.
Jon
2004 Mercury Marauder, dark toreador red/dark charcoal interior
Born On Tuesday, May 18, 2004
Sequence Nos.: 2,991 of 3,214 ('04), 10,829 of 11,052 (total) & 926 of 980 (DTRs) & 1 of 2,000 '04s without moonroof
Purchased On Friday, October 22, 2004
Sold On Wednesday, February 29, 2012
Final Miles = 099871
6 CD Trunk Changer, Heated Seats, Alternative Auto Performance Tune, Borla mufflers (#40652),
"Powered By Ford" 2005 Ford GT Coil Covers, Aeroforce OBD2 Scan Gauge, Replacement Autometer Oil Pressure Gauge,
McGard Wheel Locks (#24130), 2005 oil filter drip deflector