sure, eventually the San Andreas fault will fail in San Bernadino. If it was within a day of the M4.9, then it is pretty clear they are related. If it is a year, there will have been a lot of other things (like continued plate motion) that will have had a stronger effect...and I would not call a M7.5 or 8 a year after a M4.9 triggered by the 4.9....
Chris