Oil leak on a 2006 F-250 6.0

I recently purchased a 2006 F-250 Lariat, crew cab, 4x4, with a 6.0. It has 68k miles and is what appears to be a very well taken care of, stock (with the exception of an coolant filter kit), 1 owner vehicle. That being said, I noticed that the truck has a small oil leak between the transmission and the back of the oil pan. It leaks/weeps enough to get a drip or two on the bottom of the transmission and oil pan. At first I noticed the drip/leak was from the right side, but upon closer inspection, it appears to be damp around the base of the dipstick tube. Is there anything specific I should be looking at to tighten down before I take this into a diesel mechanic? Attached are some pictures. Thanks in advance.