As you know, there is a perfectly logical answer to this misleading finding.
Much of Pennsylvania is underlaid by coalbeds. There is such a thing as "coalbed methane" -- methane given of by and associated with coalbeds. These coalbeds -- and the associated methane -- are shallow and often within the water table. Ergo, methane and ethane were often found in Pennsylvania well water before fracking began.
Fracking is conducted in formations at depths well below the water table and where coalbed methane is found. Shale gas and coalbed methane are totally separate and unrelated deposits.
I like to tell the anti-fracking crowd to do an internet search for towns named "burning springs".