Now that i have some experience actually printing Sir Holverson: I suppose with so much tyme gone by, you have an answer, but to answer, it's a shrinkage thing: is the bed heated? enclosed build cabinet ( of course) run some preheat- now My reference is ABS, I guess PLA soesn't shrink as much,now ifyou play a particular set of heats,I fgound incresing the bed and lowering the extruder is the first thing to try- i just opened the slicer3 program, and hopefully that will take into my mbot for a very customized settings which the m bot doesn't allow 9 closed source coding)
Johnny