Methane is produced naturally in vast quantities by decaying organic matter, cow farts, released from volcanoes, natural reservoirs, etc. I doubt that some small leaks in an industrial process would make a real difference. It would probably be undetectable in comparison to the leaks in our current natural gas infrastructure that we use for heating homes, cooking, and electrical generation.
This may very well be the case that it's a non-issue, but an article that only mentions the good parts without even acknowledging potential problems with the solution makes me think "what else did they not mention that a lay-person like me wouldn't know about?".
