I accidentally turned the threaded rod while cleaning it. Have I messed up any alignments?
Perhaps. Use calipers to measure from the bed to the X-axis smooth steel rods. The rod should be parallel to the bed. If not, carefully turn one of the Z-axis threaded rods (with printer OFF) to get the X-axis rods parallel to the bed.
It isn’t a bad idea to unplug the Z-axis stepper motor before manually turning it. I usually don’t bother, but it is possible for the stepper motor to generate current when manually turned, and it is possible for that to damage the controller board.
Here’s another thread with good information. (Different cause, but same issue.)
The other way to check the level is to observe the end-stop values when the Mini goes through the auto-leveling sequence. If one of your rods got twisted, you’ll see that the end stops for one end of the bed are significantly different from the other. If they are different, you can shut off the motors and tweak one threaded rod a bit to make the end stop values come out closer, then run through the auto-leveling sequence again to double check that they are closer to matching each other. (This assumes that your bed has not been knocked way out of level to begin with - but then, so does the method of using calipers to measure up from the bed.)
A small experiment I did with rotating one Z screw (the outside easy to get to one) a little bit: https://forum.lulzbot.com/t/interesting-possible-banding-solution/2289/1
Anyway, for me it reduced banding in the Z axis – I don’t think you are going to do any harm to your printer and if you play around with it, you might get better results.
That was an interesting result in the thread you linked, Hemocyanin.
When I did mine, I just adjusted one rod until the end-stops reported during auto-leveling were as close as I could get them to agree between the left side washer touch-down points, and the right side ones. I just assumed having the x-axis rods as parallel to the bed as possible was the way to go. Before the adjustment, I was seeing the threaded rods spin a bit during a long movement along the X-axis, then spin the other way as the print head moved back the other way along the x axis. I assumed this was just the Mini adjusting for what it found during the auto-level sequence, and that it was better for it not to have to adjust (especially since there is probably some backlash in the system).
Next time I get some extended time with the printer, I’ll have to run some tests - I’ll intentionally mis-adjust the level a bit and print something similar to what you did to compare a before and after.