The solder joints fail because of vibration. I encountered this with my designs as an engineer in the telecom industry. There, relays are secured to the board in applications where vibration can be a problem. For someone who tracks their car, it might make sense to hot glue the body of the relay to the circuit board for added ruggedness.
As long as the relay contacts are not pitted, re-soldering the connections should result in a reliable device with a good service life.
One last note - I just finished re-soldering the relay connections to the circuit board on a relay that controls the power seats in my wife's SLK. And, while we don't have the problem yet, there's a similar problem in a relay that controls the fuel injection. So, Acura is not alone with solder joint problems and relays.