Thank you, Jean. I did find this in Wikipedia:
"Notable features of great blue herons include slaty (gray with a slight azure blue) flight feathers, red-brown thighs, and a paired red-brown and black stripe up the flanks; the neck is rusty-gray, with black and white streaking down the front; the head is paler, with a nearly white face, and a pair of black or slate plumes running from just above the eye to the back of the head."
Words like "rusty-gray neck" and "red-brown thighs" fit Roy's observation that depending on the time of year and they can have a purplish tinge. So maybe it wasn't that bad in the first place, but it does look better to me now.