The catch generally is that they've just begun monitoring something that was previously not monitored. In other words: There is little known about the baseline situation. Was there methane releasing in the sixties? The 1930s? The 1890s? The first of the present studies was done in 2003. Is the rate bigger than it was before - well, we can't say. There were no measurements before that time of that particular area, just assumptions.

Flux in, flux out. The only real indicator for increased methane fluxes to the atmosphere is the global atmospheric methane concentration, which showed an upward bump since 2007, after a decade of mysteriously stable values. And if I recall correctly, it wasn't even sure if the 2007/2008 bump was because of more methane coming into the atmosphere, or because rate of methane breakdown had slowed.

Figures for 2009 atmospheric methane are probably forthcoming soon, or may already have been released.