Positive for gonorrhea blood test but negative via urine test a week later?

[MadENY]

I had a full STD panel done at my general practitioner's office, including urine testing for gonorrhea and chlamydia, and all results came back negative.  However, a week EARLIER, I had blood drawn at my endocrinologist's office for different reasons and he ran of battery of lab work.  Unbeknownst to me, that lab work also included STD testing.

The lab work that the Endo ordered -- on blood that was collected a week BEFORE my urine sample (urine sample which said I was negative for gonorrhea) was submitted -- came back with a POSITIVE result for gonorrhea (1:16, when anything over 1:8 is considered positive).  This positive result was from a BLOOD test, keep in mind, not from a urine test.  Obviously, this doesn't seem to make sense, given that the later urine test showed me as negative, and I have zero symptoms and no activity in recent times that would make me likely to be at risk of anything.

Is blood testing for gonorrhea not very accurate?

I've also heard that if you have been vaccinated for Hepatitis B, which I have been, that this might cause a positive result on a blood test for gonorrhea.  Is this true?

The blood test was "N. Gonorrheae AB, CF."  The urine test a week later was "N.Gonorrhoeae RNA, TMA" performed using APTIMA COMBO2(R) Assay (GEN-PROBE(R)).

Thanks for any insight!