Not to worry!
No blood test is completely accurate all of the time. As you know, sometimes the test results indicate the presence or abscence of a disease or a condition while the opposite is true. (false positives and false negatives). For this reason several blood tests should be used to ascertain the presence of a condition indicated by abnormal results.
The ranges of "normal" values represent those found in 95% of healthy people. As you can imagine, this does not guarantee the accuracy of results. Even completely healthy people show abnormal results in some of the blood tests. Your doctor is doing the right thing by ordering another test. A repeat test does not mean anything in itself and should not be a reason for concern at this time.