  The existence of a shallow decay phase in the early X-ray afterglows of
gamma-ray bursts is a common feature. Here we investigate the possibility that
this is connected to the formation of a highly magnetized millisecond pulsar,
pumping energy into the fireball on timescales longer than the prompt emission.
In this scenario the nascent neutron star could undergo a secular bar-mode
instability, leading to gravitational wave losses which would affect the
neutron star spin-down. In this case, nearby gamma-ray bursts with isotropic
energies of the order of 1e50 ergs would produce a detectable gravitational
wave signal emitted in association with an observed X-ray light-curve plateau,
over relatively long timescales of minutes to about an hour. The peak amplitude
of the gravitational wave signal would be delayed with respect to the gamma-ray
burst trigger, offering gravitational wave interferometers such as the advanced
LIGO and Virgo the challenging possibility of catching its signature on the
fly.
