There are reasons to suppose that non-local gravitational effects may arise at sufficiently precise particle experiments, without requiring Planckian energy densities. Gravitational UV/IR mixing models predict a breakdown of low energy effective field theory, from loop-level, virtual black hole state corrections to particle processes. These models have previously been proposed as a way to resolve the cosmological constant problem. I will discuss recent work computing a matter effect for gravitational UV/IR mixing and show that the Brookhaven muon g-2 measurements can already be used to explore this class of theories.