YES! THIS! I'm noticing it on the 16-35. On close subjects it seems OK, but on landscape shots at infinity (or far away focus) I can't seem to get past the blurry/hazy extreme corners...I almost thought the lens was defective, actually, until I examined some of the shots I took at closer distance....weird.
Interestingly, and I admit my knowledge is limited on this, lens resolution/performance can vary with focusing/subject distance, and annoyingly this factor is rarely mentioned or tested by many lens testing sites. My 17-40 and EF-S 10-22 are both similar in this regard on the 7D, at close distances even to the edges of the frame the sharpness is pretty good, but for infinity subjects at the corner of the frame it's a different matter. Obviously, factors such as CA, field curvature and astigmatism have a part to play, and resolving fine detail on small and distant subjects is always going to be a bigger test of a lens than closer subjects.