Interesting statement. George W. Bush is President number 43. If he is re-elected, he remains number 43. He cannot be number 44. If he serves non-consecutive terms, he will be number 45 or higher (as in the case of Grover Cleveland).
Now, if the "BUSH" you refer to is Jeb, or even George Herbert Walker Bush again, then you are correct.
No, he will still be our 43rd President, but he will serve 2 terms. (Ronald Reagan served 2 terms, but he was our 40th President, not 40th and 41st.)