Surprising behavior of atsc_field_sync_demux

I am seeing a surprising behavior with atsc_field_sync_demux:
every time i run it i get slightly different results (in terms of
output file sizes/values).

I have uploaded two testfiles here (they are the two equalizer output
streams):

http://www.eecs.umich.edu/~anastas/gnuradio/atsc_4eq0
http://www.eecs.umich.edu/~anastas/gnuradio/atsc_4eq1

and the python test script:

http://www.eecs.umich.edu/~anastas/gnuradio/eq-fsd.py

I would appreciate if someone can verify this behavior.

Achilleas