In photoluminescence spectroscopy of a low-mobility two-dimensional electron gas subjected to a quantizing magnetic field, we observe an anomaly around nu=1/3 at a very low temperature (0.1 K) and an intermediate electron density (0.9x10(11) cm(-2)). The anomaly is explained as due to perturbation of the incompressible liquid at the Laughlin state due to close proximity of a localized charged exciton which creates a fractionally charged quasihole in the liquid. The anomaly of similar to2 meV can be destroyed by applying a small thermal energy of similar to0.2 meV that is enough to close the quasihole energy gap.