one can never be too paranoid. I was updating the firmware on my router one day to resolve an issue (coincidently given the recent topic of "Macs", to resolve a Mac issue whereby only the Mac's on my network had serious internet speed and connectivity issues), and in the process of doing so had to reset to factory defaults (which took down my WPA security for the moment)
In the space of the less than 10 minutes it took to update and reset up my network customization and security....an evesdropper had logged into my SSD for some free Internet and was attempting to access the router for his or her own nefarious purposes (the IP showed up on the DHCP log page) Better, the intruder then attempted to mess with my router settings forcing me to unplug the thing, turn it back on and immediately reset my password.
Kind of scary. A simple 10 minute window of vulnerability and some script kiddie tries to hijack my home network. I regularily check my log now and am seriously considering setting up a MAC list.