well i just looked on international cannibis forums and seen over watering makes your plants look like they do so maybe your soil is holding the water longer then you think and when you water it builds up ??? making the plant get overwaterd just puttin my two cents in as im still new here is a link to the forum
http://www.icmag.com/ic/showthread.php?t=11688 and its about half way down where the over watering section is