None at all, nor would I have expected it. The only suspension position in which contact between caliper and caster arm is possible is almost fully extended, with the wheel's leading edge pointing inwards with two thirds lock.
Under pretty much any driving circumstance, those two conditions are basically mutually exclusive. With the steering in that position, the suspension on that side will be compressed, not extended.
Unless of course, you get big air mid corner in which case there's other, more Armco-ish things to contend with
Oh, and btw.. there's no marks on the calipers either, which lends credence to the theory.
