Of course he did. But I can not think of a justification available to Aristotle that wouldn't equally justify that Sun revolves around the Earth. Yet "Aristotle knew that Sun revolves around the Earth" would be seen as a misuse of "knew". Did Aristotle know that water is heavier than air? Sure, but to him it meant that the natural place of air is above the natural place of water. Are we still answering "yes"? Did he know that the universe is finite? Did Newton know the law of inertia? Keep in mind that to him inertial motion happened relative to the absolute space, and means of formulating the law without it weren't worked out until late 19th century. Did Eistein know about the dark energy? Cosmological constant was introduced to stabilize the universe, not to accelerate its expansion.
These are historical examples of the Gettier problem of knowledge as justified true belief (JTB), when a person is justified in her belief, and the belief is true, but the justification relies on elements that are false. To put it plainly, a person believes the right stuff for the wrong reasons, but this "wrongness" is external to justification. Officially, Gettier knowledge is not knowledge, but "X knew that p" is colloquially interpreted as "X believed that q, which is translated into modern terms as p, and comes out as true", otherwise if X still believed that q then "X mistakenly believed that p".
I used to think that Kuhn's "incommensurable paradigms" are an exaggeration, and perhaps they are, but there is a genuine problem there. Let us grant downward correspondence, that is that "less advanced" paradigms can be imported into "more advanced" ones using anachronistic translation, and cheerfully assume that today we know what's true. This still leaves the problem of Gettier knowledge. The justifications historical figures had for their beliefs invariably depended, at one place or another, on something that we now hold false. People often ask on the history site if people knew p before modern times, or who first discovered p. I usually give a colloquial answer, with reservations, and then try to explain how modern concepts emerged, and differ from the historical ones. Is there a more principled way? Kuhn's dissolution of the question as meaningless seems extreme, but the colloquial interpretation is hardly a satisfactory philosophical position.
What do we count as "knowledge" in centuries past? How do we measure dependence on "false lemmas", and how slight is it supposed to be to still produce knowledge? What are the approaches to the Gettier problem in the context of the history of science, in particular concerning the growth of knowledge? How is the flaw it reveals in the notion of the downward correspondence addressed? Are alternatives to JTB, that SEP barely mentions, more suitable in historical contexts?