[Colin2B]

the field has an apparent mass, dictated by the energy stored within the field. Therefore, a magnetic field would fall into a gravitational well. .........Gravity distorts spacetime and therefore must affect anything that propagates through space. In the same way that light is diverted by gravitational wells, presumably the field lines would be similarly affected.

I'm no expert either, but as the electromagnetic stress tensor contributes to the energy stress tensor then it must have an effect. However, I did see a calc that suggested that the entire earth's mag field results in an equivalent mass of about 100kg, so we are unlikely to see an everyday effect.