Without getting into the argument about why bonuses to social actions should not be considered to automatically apply to mental attacks that happen to use the same skill, I'm going to replay to the original topic:
"The downside, of course, is that people tend
to see you as a representative of the thing
that marked you, which can lead to some
uncomfortable entanglements and assumptions."
So basically, you get the occasional +1 to social skills (which only applies in situations in which the mark is recognized as such, and not when interacting with, for example, any non-clued mortals) balanced by the fact that all of your patron's enemies are guaranteed to recognize you with a casual glance. To be honest, I agree with the OP; it makes sense to housrule this to -0.