...and it was so unusual that they lampshaded it by having Al comment on how he wasn't in the US.
Plus, he was a vampire.

I think it's fair to say that "Blood Moon" is an atypical episode.
Having Sam Leap into an American soldier in Vietnam, an American defector in Moscow, or an American archaeologist in Egypt doesn't do a lot to make the series come across as less Americentric (especially when you're a non-American viewer in an English-speaking country never featured on the show).
The earlier list of episodes "outside the US" in this thread also included three examples where Sam is at sea (with other Americans), which is something of a stretch if you're trying to sell this particular argument.