I seem to remember seeing these replayed on later Sesame Street episodes. Anyone else have that feeling?

Could be. Sesame Street frequently ran repeated bits -- kids, especially little kids, learn better that way, or so I hear (that's why the Teletubbies like to yell "again" and watch a clip again).

What fascinates me about those clips is that they don't expressly seem to teach anything -- there are some subtle geometric and primary/secondary color lessons implied but it's not nearly as instructional as nearly everything I've seen on Sesame Street is. Unless maybe the original clips had a voice-over?

Subway!