Probably. Vignetting can be common on wide angle lens wide open, especially on FF bodies. Do some testing by taking photos of a white wall with different aperture settings and compare those photos. Then take some photos at different focal lengths to see where the vignetting begins.
As long as the vignetting is the same in all 4 corners of the photo, the lens is not an issue. If it's uneven, the lens will need to be sent into canon for centering the elements.
Stacking filters or having a wrong lens hood (or even the correct hood improperly attached) can also cause vignetting. Do you have a filter on this lens? If so, is the ring thickness unusually wide? Do you get vignetting without the filter?
Some links to investigate further: