Epson 3880 one head picks up air bubbles

I'm using the Inkjet Fly Small Foot cartridges which appear to be the same as the Cone Color ones on my 3880. In over a year's use I've been generally very happy with the ink and cartridges, however there is one oddity. My cyan cartridge is susceptible to air bubbles after sitting for more than 2 or 3 days, particularly if the printer has been turned off whereas I've never seen a skip on any of the other colors. I got a replacement cartridge from IJF, but the problem is unchanged. Just printing a sheet of all cyan on plain paper fixes it every time, so it's not a huge problem, but I was wondering if anyone had any thoughts.