2005 Dodge Truck Power Steering leak

Hello, i have just noticed the last few days a leak under my truck. It appears like the power steering fluid. I checked the fluid a few days ago, 9/13/08 an d that's when i first noticed the leak and the reservoir was a bit low.. i added fluid and its not low yet still has a slow leak. The funny thing is it won't leak during the day when I"m operating it, it only starts the seeping leak at night when its totally cooled for like 6 or more hours... i've attached some pics below as i got down underneath it since i don't want to go to a shop and they would be like..we don't see a leak. I'm wondering if its because of a seal and that when its hot, it expands and seals and when its cooled it shrinks possbly causing the leak. Again pics are attached.. any advice is welcomed so I can fix this with minimal cost.