  Because the propagators of flavor-singlet states incorporate disconnected
diagrams, they are uniquely sensitive to any differences in the actions
governing sea and valence fermions on the lattice. As such, they present an
important test of the validity of the ``fourth-root trick'' in the staggered
fermion formulation. The pseudoscalar's relationship to topological charge also
makes it of theoretical interest. We present preliminary results from our
measurements of flavor-singlet pseudoscalar mesons on 2+1 flavor Asqtad
lattices, and discuss some strategies for improving the signal-to-error ratio
of disconnected singlet correlators.
