Print issue ?

[Recrem]

Hi 

I have recently scaled up an image produced with Gimp to print 83 x 50cm. I generally produce the image at 50 x 30cm but had a special request for a larger image. 
I've printed at the smaller size and never noticed any problem.. haven't had any similar problem in ten years of producing and printing images. 

I was surprised to find the printed image was larger on the left side than on the right by 3mm. 

I went back and checked the digital image thinking the image must have been distorted by the "unified transform tool" and left short on the right side.. but found on checking that the image completely filled the 83 x 50 rectangle with no visible empty background ? 

We have since printed the same image twice and it is still 3mm short on the right side. 

I am not certain if this problem has originated in Gimp or via the printer software.. I sent the image to a printer as a jpeg and they checked it in PS before printing.  
Are there any known issues with certain printers.. or image file formats ? 

Has anyone encountered this issue before ?

And if they did how did they resolve it ? 

Thanks in anticipation.