Strange Oracle results with sysdate in query

I am getting very strange results when I use "sysdate-30" in a query. Is this a bug in Oracle? I get same results from TOAD, SQL Plus on Windows PC and SQLPlus on my (Unix) Lawson server.

If the sysdate check is first I get incorrect results. If the sysdate check is second I get the correct results.

Below is a sample of the query I was trying to run followed by a query that does return the correct results. The only difference is if the sysdate clause is before or after the OR statement. These queries have lots of parens , I tried with varying numbers of parens with no difference in results.


Oracle Database 11g Release 11.2.0.1.0 - 64bit Production

-- Incorrect results
SQL> select count(*) from employee emp
    where
    (emp.TERM_DATE >= (sysdate-30)) OR (emp.TERM_DATE = TO_DATE('01/01/1700', 'MM/DD/YYYY'))
    ;

  COUNT(*)
----------
         5       

--Correct results
SQL> select count(*) from employee emp
    where
    (emp.TERM_DATE = TO_DATE('01/01/1700', 'MM/DD/YYYY')) OR (emp.TERM_DATE >=(sysdate-30))
    ;

  COUNT(*)
----------
      1506

SQL>