We find using Monte Carlo simulations of the 2D square lattice nearest neighbour quantum Heisenberg antiferromagnet that the high energy peak locations at (pi,0) and (pi/2,pi/2) differ by about 6%, (pi/2,pi/2) being the highest. This is a deviation from linear spin wave theory which predicts equal magnon energies at these points. It is also found that the peak at (pi,0) is broader than the peak at (pi/2,pi/2).