  In view of the recent report by Connaughton we analyse continuous TTE data of
Fermi-GBM around the time of the gravitational wave event GW 150914. We find
that after proper accounting for low count statistics, the GBM transient event
at 0.4 s after GW 150914 is likely not due to an astrophysical source, but
consistent with a background fluctuation, removing the tension between the
INTEGRAL/ACS non-detection and GBM. Additionally, reanalysis of other short
GRBs shows that without proper statistical modeling the fluence of faint events
is over-predicted, as verified for some joint GBM-ACS detections of short GRBs.
We detail the statistical procedure to correct these biases. As a result, faint
short GRBs, verified by ACS detections, with significances in the broad-band
light curve even smaller than that of the GBM-GW150914 event are recovered as
proper non-zero source, while the GBM-GW150914 event is consistent with zero
fluence.
