  We investigate the issue of single particle nonlocality in a quantum system
subjected to time-dependent boundary conditions. We first prove that contrary
to earlier claims, there is no strong nonlocality: a quantum state localized at
the center of a well with infinitely high moving walls is not modified by the
wall's motion. We then show the existence of a weak form of nonlocality: when a
quantum state is extended over the well, the wall's motion induces a current
density all over the box instantaneously. We indicate how this current density
can in principle be measured by performing weak measurements of the particle's
momentum.
