I've seen this with ABS, PLA, and now PETG. I've tried changing the temp, but it still happens. I have a Makerfarm I3V 10" with the hexagon hotend. It seems like it only happens on thinner walled areas, so I created a simple test object and, sure enough, an entire side is patterned that way. The other sides had a little of the pattern, but not much. The opposite side has some diagonal banding I've been seeing on a lot of prints too.
http://imgur.com/a/U3RIw
Any ideas?
Thanks in advance, Matt