I suspect he's implying he "grounded" his antenna by replacing his magnet mount with a permanent-mount.
Certainly that is the best way to go, however I suspect there may have been another issue at play (something preventing the magnet mount from working correctly, or the mount itself being defective)...
A magnet mount antenna's ground works via capacitive coupling (this is why most mounts have a piece of foil over their bottom surface). They do not need a separate ground wire or a physical DC connection to function.
When you place the mount against the vehicle, it's foil bottom in proximity to the car's steel creates a capacitor (with the paint as it's dielectric) that carries the antenna's ground current through to the steel body (even though there's no DC connection, it's capacitance still presents a current path of less than an ohm (often much less) at 27 million cycles/second AC, the radio frequency your CB transmitter operates at).
Some info about how capacitors work here:
http://en.wikipedia.org/wiki/Capacitor
(warning, very technical)
Something that can prevent mag mounts from working properly is the common practice of putting pieces of cardboard or other thick items under the mount in an attempt to protect the car's paint. Such items increase the mount's distance from the steel, which not only decreases the magnet's holding power, it also reduces the capacitance underneath the mount, increasing it's impedance to ground (not sure if that was CCPA's issue, or could it be yours?). Those worried about their car's finish, make sure whatever you use is thin like a single sheet of bath tissue or a piece of cellophane (layered-up paper towels is a no-go here).
Also, I don't disagree with BigJimCruising's comments about checking everything you can, however the power wires shouldn't be something that affects your SWR. A bad SWR almost always is a result of issues with the antenna system. If changing the power wires around
did affect the SWR, this would indicate a deficient ground in the antenna system, as under no circumstances should there be RF current flowing on your power wires.