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V391 Peg (alias HS2201+2610) is a subdwarf B (sdB) pulsating star that showsboth p- and g-modes. By studying the arrival times of the p-mode maxima andminima through the O-C method, in a previous article the presence of a planetwas inferred with an orbital period of 3.2 yr and a minimum mass of 3.2 M_Jup.Here we present an updated O-C analysis using a larger data set of 1066 hoursof photometric time series (~2.5x larger in terms of the number of datapoints), which covers the period between 1999 and 2012 (compared with 1999-2006of the previous analysis). Up to the end of 2008, the new O-C diagram of themain pulsation frequency (f1) is compatible with (and improves) the previoustwo-component solution representing the long-term variation of the pulsationperiod (parabolic component) and the giant planet (sine wave component). Since2009, the O-C trend of f1 changes, and the time derivative of the pulsationperiod (p_dot) passes from positive to negative; the reason of this change ofregime is not clear and could be related to nonlinear interactions betweendifferent pulsation modes. With the new data, the O-C diagram of the secondarypulsation frequency (f2) continues to show two components (parabola and sinewave), like in the previous analysis. Various solutions are proposed to fit theO-C diagrams of f1 and f2, but in all of them, the sinusoidal components of f1and f2 differ or at least agree less well than before. The nice agreement foundpreviously was a coincidence due to various small effects that are carefullyanalysed. Now, with a larger dataset, the presence of a planet is moreuncertain and would require confirmation with an independent method. The newdata allow us to improve the measurement of p_dot for f1 and f2: using only thedata up to the end of 2008, we obtain p_dot_1=(1.34+-0.04)x10**-12 andp_dot_2=(1.62+-0.22)x10**-12 ...

The sdB pulsating star V391 Peg and its putative giant planet revisited after 13 years of time-series photometric data