Issue with Epson 7900.......
These are drips off the bottom of the print head. I have a 9890 and this will occur is I have to do 3 cleanings (usually a couple pairs, or after doing a PK->MK change or visa-versa.
There are two things you can do. Clean the wiper blade, and clean the underside of the print head.
For detail instructions on how to do this, head over to luminous-landscape.com forum:
Eric even did a video on how to clean the wiper blade, and somewhere in that endless thread are instructions on how to release the print head which will allow you to run it over a dampened sheet of paper towel or pec pad.
Hope that helps.