Sudden Y-Axis Shift

Hey I was just wondering if anyone had experience with this problem, I've been using my Robo PLA only model for about a week now and I was printing my first big print and something weird happened. It was almost like the layers of the statue I was printing suddenly shifted to the +y direction, but printed well other wise. Today when I went to print something else and tried to home my y-axis it kept making the noise when it homed the y axis as if it thought it could go back farther than it should have, this would correlate with the shifted layers. Does anyone have any idea what caused the shift I imagine something with the motor is now mis calibrated, anyone able to shed some light on this?

*Edit Uploaded a picture of the print I referred to.

 

I had the same thing today clicked x home and the x just kept trying to drive to the left even though it was on the stop switch. probs just a firmware bug. I sometimes have an issue where the extruder doesn't heat up or some times the heat bed but more often its the extruder I just exit the software and restart it and click manual and start them both manually before I start the print. I guess that's just the joys of bundling software with loads of different firmwares

 

Yeah, I was fully prepared to tighten the belt or screw or whatever needed done, however when I went to go fix it yesterday the issue apparently just disappeared.