  Recently LHCb has announced a discrepancy of 3.7 sigma in one of the
theoretically clean observables accessible through studies of angular
correlations in B->K*mu+mu-. We point out that in the most minimal Z' setup
that can address this anomaly there is a model-independent triple-correlation
between new physics (NP) in B->K*mu+mu-, B_s-Bbar_s mixing, and non-unitarity
of the quark-mixing matrix. This triple-correlation can be cast into a simple
analytic formula that relates the NP contribution DeltaC9 to the Wilson
coefficient of the semileptonic vector operator to a shift in the mass
difference DeltaM_{B_s} and a violation of |Vud|^2+ |Vus|^2+ |Vub|^2 = 1. In
contrast to the individual observables the found relation depends only
logarithmically on the Z' mass. We show that that our findings allow for useful
future tests of the pattern of NP suggested by the B->K*mu+mu- anomaly.
