Has anyone else been having vector illustrations rejected for the following reason at Shutterstock

QuotePlease decrease the size of your artwork (or move it) to fit within the artboard.

Do they really want a border around all illustrations? or is it just one of those blanket rejection reasons.

I could be way off, but it sounds like they want you to fix the part of your illustration that is hanging off the artboard? Or maybe adjust the size of the artboard to accommodate the whole illustration?

I use Xara Xtreme 4 instead of Illustrator but usually resize the artboard
to fit my work and center everything so that nothing is outside. Seems to work.

Just checked one of the rejected illustrations the illustration is 1600 x 1600 pixels and the page size is 1600 x 1600, so no overhanging bits there 

On Shutterstock you should have vector image sized not more than 5MB.
If you have some objects hanging off the artboard that is no-no!

Not border needed there - just take care about your illustration is placed on artboard and nothing is showing off it!