Yep, CH4 + O2 is at least as dangerous as pure O2
There have, of course, been attempts to mitigate the problem of methane buildup on long-duration missions. Notably, Mir was equipped with a system called the Free-Radical-Ozone Methane Analysis and Gas Experiment, which showed some promise. However, because it was a late retrofit, its circuit breaker was clumsily installed on a panel where inhabitants would frequently brush up against it and shut down the system. The system was quiet and often nobody noticed for a while. It was a visiting French astronaut who coined the immortal phrase, "Ewww, cheeze, has somebody cut ze FROMAGE once again?"
I'm soooo sorry.