I did a 1gal Caribou Slobber kit a little while back that had bad soapy off flavors. I spoke with a trusted friend and the folks at Northern Brewer and both said the same thing, it sat on the yeast too long. And it was there for three weeks.
Meanwhile, on this (and other) forums I always hear of people letting their primary sit for much longer than that. I was explained it was due to the fact it was a 1gal kit and the approximate yeast measurement.
Instructions say to pitch 1/2 of the yeast packet. In my rush to brew, I hydrated the entire packet. Once it came time to pitch, I swirled the yeast into suspension and poured off just a hair over 50% of the yeast into the wort to "fix" where I went wrong.
The employee @ NB put it to me pretty plainly... The yeast packet is designed for a 5-6g batch. You (at our recommendation/instructions) put half of that into a batch that's 20% of the "normal" recipe. So overpitched. This makes the fermentation a bit faster but you run a greater risk of autolysis.
Armed with that knowledge, I did another 1g NB kit (BV Hefe). I poured out the yeast packet and measured 1/2 of it precisely and hydrated and pitched. This time I pulled it off the primary after 10 days. 4 days of good fermentation/bubbling and about 3 days of complete inactivity. I figure my fermentation was actually finished around day 6. I bottled it this past weekend and will pop the first one at 10 days. This batch tasted fine prior to bottling so we'll see.