  The photometric light curve of PG1302-102 shows periodic variability which
makes this object one of the most plausible supermassive black hole binary
candidate. Interestingly, the most recent study of its updated optical light
curve reports a decrease in significance of periodicity which may suggest that
the binary model is less favorable. Here, we model the PG 1302-102 light curve,
spanning almost 20 years, with a supermassive black hole binary system in which
a perturbation in the accretion disk of more massive component is present. Our
model reproduces well the observed light curve with a slight perturbation of a
sinusoidal feature and predicts that a slightly larger period than previously
reported, of about 1899 days, could arise due to a cold spot in the disk of
{\bf more massive} component of a close, unequal-mass
($\frac{\mathrm{m}_{1}}{\mathrm{m}_{2}}=0.1$) black hole binary system. The
light curve resembles the pattern of sinusoid-like shape within a few years,
which could be confirmed by future observations. In addition, using our hybrid
method for periodicity detection, we show that the periods in the observed
($1972\pm 254$ days) and modeled ($1873 \pm \ 250$ days) light curves are
within one-sigma, which is also consistent with our physical model prediction
and with previous findings. Thus, both the periodic nature and its slight
fluctuation of the light curve of PG1302-102 is evident from our physical model
and confirmed by the hybrid method for periodicity detection.
