And one more thing to keep in mind about re-testing: re-testing within two years of the last test is generally considered invalid, so if you re-test six months from now, you won't be able to re-test again for another two years, which is 2.5 years from now, which may or may not affect the next opening for gifted programming.
Odds of his score changing largely depend on the validity of the original test. If the low score is real (for that task), then it won't change much, and, honestly, you have just as much of a chance of some of the higher scores dropping slightly, offsetting any gains. If the original subtest was not valid, then it might change, but it doesn't appear that the examiner gave any indication that it might be invalid. Index scores are more stable than subtest scores, in general.
