There are a couple of causes of that, some you can deal with, some that are more difficult to deal with. To understand what is going on, you have to think about what is happening when you lay down a layer. When you start a new layer, your printer goes to a new point, starts extruding which usually results in a bit of excess flow depending on your settings, then it starts to move to the next point at a constant acceleration, getting fastest at the midpoint, and slowing down until it makes the transition to the next turn or curve or or corner, etc. But you have multiple acceleration pieces in place here. With a Taz, the nozzle itself moves in X and Y, and is moving whenever you have a flat section in the X direction, but is stationary whenever you are doing a flat section in Y. What you will sometimes see with 3d printers, and what you are seeing in this case, is that after a transition From X to Y, or after a stop and restart of motion in X or Y, you will sometimes get a bit of excess extrusion from the sudden start of acceleration. You can see a much exaggerated version of that happen when a top fuel dragster or a funny car does a high speed pass. The front wheels come up off the track due to the intense acceleration, and then usually bounce a couple of times before smoothing out, even though the car is still going faster.
With a 3d printer, it’s a bit of the same thing. You can minimize it by cleaning any excess fuzz off the bearings, making sure you have no excess play on the bearings themselves, going with harder rods, making sure your belts are super tight, etc. The phenomenon is often known as “ringing” because in bad cases, it often shows up as an after image ring of a hole. A little bit of it is normal, and you will never be able to get rid of it entirely unless you decide to go print out in space, but you can improve it to where it isn’t noticeable anymore.