strange infinite loop in plpgsql

I've been reading the online docs, but... code like this somehow ends up
in an indefinite loop:

CREATE OR REPLACE FUNCTION foo() RETURNS int AS $$
DECLARE
   timeout int;
   day date;
BEGIN
     day := current_date + 1;
     LOOP
       SELECT date+1 INTO day FROM days WHERE date=day OR EXTRACT(dow
FROM day) IN (0,6);
       EXIT WHEN NOT FOUND;
       timeout := timeout + 86400;
     END LOOP;
END; $$ LANGUAGE plpgsql;

It's Saturday at our place, and the "days" table has only one record for
tomorrow's date.

I hope it's been a very very long day for me :-) Thank you for your help.