Keep in mind that very large quakes occur on (usually larger) faults that have not had any major (or sometimes any) activity for a long time. The pressure on faults is always building. Smaller, more frequent quakes relieve the stress and help prevent massive quakes, so having lots of four-pointers and an occasional fiver isn't really a bad thing.
Even low fives aren't that bad because of the strict construction requirements in California. We had aftershocks larger than 5.0 after the Northridge quake and those of us who were near ground zero in the main quake just shrugged them off. I knew one person who got nervous when a +5 aftershock hit while we were together, but that person was over 30 miles from the San Fernando valley when the main quake hit and hadn't experienced the difference.