Shift/moved print  

RE: Shift/moved print

Usually caused by a crash on the axis, in this case your x axis from the look of it (assuming the part was on the bed in the same orientation). 

When you move the extruder back and forth by hand along that axis does it feel smooth and even ?  If not then you need to lubricate your bearings.  A quick temporary job can be done by using a light machine oil applied to the rods and worked past the seals by moving it back and forth.  That's only a stopgap method though.  If your bearings do need lubricating then the only way to do that is properly is disassembly and applying bearing grease inside them.

RE: Shift/moved print

Moving all the axis by hand seems fine. I oiled the rails with 3-in-1..............can't get any lighter than that. I will wait and see if it happens again.

As for the greasing part, the printer is only 6 months old. Should I really be concerned about that with such a short run time?

RE: Shift/moved print

Opinion differs on that.  The official line is that bearings come pre-lubricated.  However several users (and other engineer friends) say that the bearings are shipped from the manufacturers with a protective coating that is designed to stop corrosion and is not really a lubricant.  Personally I'm in the latter group.

I have seen posts on here where bearings have started to have issue in much less than 6 months, others take longer.  I suspect its a combination of luck and how much you actually use your printer.  I was aware of this discussion before assembling mine so I cleaned out the shipping grease and fully lubricated my bearings before initial assembly.  I then ran my printer for about 18 months, usually printing 20-60 hours a week.  With not an issue.

I did some part upgrades after that (geared extruder, different x axis ends etc) that meant the printer would be partially disassembled so I took that opportunity to clean and re-grease my bearings at the same time.  Its now been around another 12 months of trouble free printing.

Sorry, that a pretty long winded way of saying yes, its a possibility. 

Of course it could also be you had a raised bit of filament sticking up on your part that caused a collision, or possibly a loose pulley, but I don't think so looking at the picture as those usually cause back and forth shifts.  Worth checking though.

RE: Shift/moved print

It looks like prusa isn't sure either. 

In the manual for the Mini they tell you to lube the bearings. And it looks like they even added the tool to do that.

https://help.prusa3d.com/en/guide/2-yz-axis-assembly_196824#196964