Could be a wiring issue also. I always suspect wiring first on swapped cars, mostly because of some of the wiring nightmares I've seen.. So keep that in mind, it could be a poor connection or something like that. Could be a sensor power or sensor ground problem because it's affecting more than one sensor.

Keep an eye on it and see if comes back, other than that it's just about impossible to troubleshoot when it's working properly.