NOTICE: generated by sequence nextval()

Postgresql 7.1.3-2
Red Hat 7.2

I've noticed that if I create a sequence, and then do a select on it using nextval() everything works fine. However, if I drop the sequence and then create it again, the same select statement generates a NOTICE.

Is this normal behaviour or a bug? See below.

test=> create sequence serial;
CREATE
test=> select nextval('serial');
nextval
---------
1
(1 row)

test=> drop sequence serial;
DROP
test=> create sequence serial;
CREATE
test=> select nextval('serial');
NOTICE: serial.nextval: sequence was re-created
nextval
---------
1
(1 row)