I looked at data prior to 2010-09-12 (a camera change date), to see if there was any difference in the bathtub rings. The bathtub rings are still there, but fainter. I started with the first non-dark exposure of the night, and found the video cells (this is where I have found the rings before). I looked at the exposure before a video cell to see if there were rings, and there never were. Here is what I found:

exposure	video cell?	bathtub rings?
o5409g0021o	xy33	none
o5409g0022o	xy33	none
o5409g0023o	xy52	xy33
o5409g0024o	xy52	xy33
o5409g0025o	xy01	xy33,xy52
o5409g0026q	xy74	xy33,xy52,xy01
o5409g0027q	xy23	xy33,xy52,xy01,xy74
o5409g0028o	no	none (I expected them on xy33,xy52,xy01,xy74,xy23)
o5409g0029q	no	xy52,xy33 (not on xy74, xy23, or xy01 )
o5409g0030q	xy51	xy52,xy33, xy01 (not on xy74, xy23 )
o5409g0031o	xy74	xy33, xy51 (not on xy23,xy52,xy01 )
o5409g0032o	xy22	xy51 (not on xy23,xy74,xy52,xy33,xy01 )
o5409g0033o	no	none (I expected them on xy22,xy51,xy23,xy74,xy52,xy33,xy01)

Typical 2010-08-01 bathtub ring. These are fainter than the ones from 2010-09-25, and sit on the ground.