Thanks, doc_c! That's it! There is a term for it! And, what's more, it does seem to be considered the opposite of deja vu, which I find a bit surprising, but. There are seven hits on OneLook and all concur:

jamais vu

n : the experience of being unfamiliar with a person or situation that is actually very familiar; associated with certain types of epilepsy

Source: WordNet ® 1.6, © 1997 Princeton University
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And from the Online Medical Dictionary:

jamais vu

From the French, meaning never seen, the illusion that the familiar does not seem familiar, the opposite of the feeling of deja vu.

(12 Dec 1998)


disoriented

Disorientation doesn't quite fit because you're not really disoriented...you're still cogent, you can still drive, think, converse, react, know who you are, etc...it's just that the surroundings seem suddenly unfamiliar...a pretty cool feeling actually for a short while (as long as you come out of it).