  There has been disagreement in the literature on whether the hydrogen atom
spectrum receives any tree-level correction due to noncommutativity. Here we
shall clarify the issue and show that indeed a general argument on the
structure of proton as a nonelementary particle leads to the appearance of such
corrections. As a showcase, we evaluate the corrections in a simple
nonrelativistic quark model with a result in agreement with the previous one we
had obtained by considering the electron moving in the external electric field
of proton. Thus the previously obtained bound on the noncommutativity
parameter, $\theta < (10^4 GeV)^{-2}$, using the Lamb shift data, remains
valid.
