  Previous studies suggest that tidal interactions may be responsible for
discrepancies between the ages of exoplanet host stars estimated using stellar
models (isochronal ages) and age estimates based on the stars' rotation periods
(gyrochronological ages). We have compiled a sample of 28 transiting exoplanet
host stars with measured rotation periods. We use a Bayesian Markov chain Monte
Carlo method to determine the joint posterior distribution for the mass and age
of each star in the sample, and extend this method to include a calculation of
the posterior distribution of the gyrochronological age. The gyrochronological
age ($\tau_{\rm gyro}$) is significantly less than the isochronal age for about
half of the stars in our sample. Tidal interactions between the star and planet
are a reasonable explanation for this discrepancy in some cases, but not all.
The distribution of $\tau_{\rm gyro}$ values is evenly spread from very young
ages up to a maximum value of a few Gyr. There is no clear correlation between
$\tau_{\rm gyro}$ and the strength of the tidal force on the star due to the
innermost planet. There is clear evidence that the isochronal ages for some
K-type stars are too large, and this may also be the case for some G-type
stars. This may be the result of magnetic inhibition of convection. There is
currently no satisfactory explanation for the discrepancy between the young age
for CoRoT-2 estimated from either gyrochronology or its high lithium abundance,
and the extremely old age for its K-type stellar companion inferred from its
very low X-ray flux. There is now strong evidence that the gyrochronological
ages of some transiting exoplanet host stars are significantly less than their
isochronal ages, but it is not always clear that this is good evidence for
tidal interactions between the star and the planet.
