This should really be a yes/no answer, or?
Pictures or from "Petrie - The pyramids and temples of Gizeh (1883)":
[...] At the corners, however, the casing was thinner, averaging but 33'7 ( difference of core plane and casing on pavement); and this is explained by the faces of the core masonry being very distinctly hollowed.
This hollowing is a striking feature; and beside the general curve of the face, each side has a sort of groove spedaily down the middle of the face, showing that there must have been a sudden increase of the casing thickness down the mid-line. [...]
p. 43,44
if you don't get an answer here, it might be worth x-posting this to one of /r/AskAnthropology, /r/Archaeology, /r/AskScience (Social Science category)
There is some evidence that the sides of the Great Pyramid are slightly concave:
Remember that that the casing stones have all been stripped off. The sides were probably perfectly straight when the casing stones were present.
