This is an issue that's started happening recently. This is a Prusa I3 using a 1.75mm
pla filament
The settings for this print are as follows
Layer height: 0.2mm
Line width: 0.4
Infill: 60%
Infill pattern: Triangles
Nozzle temp: 190C
Plate temp: 60C
Retraction distance: 8.5mm
Retraction speed: 60mm/s
Print speed: 50mm/s
Cooling fan speed: 20%
This happened on a previous print, but not as much. The only difference is the other print was printed 10mm/s faster. I'm thinking it has to do with too much time in a certain area since it seems to happen in pretty small areas that don't required infill and print as two walls back to back