  In a recent paper, Hagelstein and Pascalutsa examine the error associated
with an expansion of proton structure corrections to the Lamb shift in terms of
moments of the charge distribution. They propose a small modification to a
conventional parameterization of the proton's charge form factor and show that
this can resolve the proton radius puzzle. However, while the size of the
"bump" they add to the form factor is small, it is large compared to the total
proton structure effects in the initial parameterization, yielding a final form
factor that is unphysical. Reducing their modification to the point where the
resulting form factor is physical does not allow for a resolution of the radius
puzzle.
