Methane isn't great, but unlike CO2 is has a pretty short lifetime in the atmosphere (just 12 years). So the impact of the methane release from hydro is basically static rather than an ever increasing problem.
This is not true! Methane is not only 84x more warming than CO2, it is at a record high at <1900ppb and rising, the current level is higher than the RCP 4.5 warming scenario by the IPCC (which is in the middle level of a warming scenario), and there is evidence that the atmospheric lifespan might be increasing
> A molecule of methane traps more heat than a molecule of CO2, but methane has a relatively short lifespan of 7 to 12 years in the atmosphere, while CO2 can persist for hundreds of years or more.
Doesn't mean it's correct though so I'd be happy to see different thinking on this.
That being said, IIRC, isn't one of the models for the increasing methane the melting permafrost [2]? So the levels are somewhat expected to be increasing pretty rapidly as a result of global warming in general.