Several thoughts - in that month have you done anything that would elevate your testo levels : proviron, avena, clomid, vitex etc?
Lab reference ranges may differ - I am SURE you did not have the salivary tests done at the same lab that did the blood tests. Labs differ in their reference ranges ("normals"). You can have a liver test done at Quest diagnostics and have it done the same day at Labcorp - and get the same value (for example lets just say 60 for SGPT) - Quest would consider that a normal SGPT but Labcorp would mark it as slightly out of range. This is bacause all labs make up their own ranges (except for cholesterol and glucose) by taking the average of all their blood tests in a given year, throwing out 2 standard deviations and then averaging it. The trouble with this is that most lab tests are done on sick people, so we are possibly getting an average of what the average sick person looks like. They try to remedy this by tossing out the 2 standard deviations - the highs and the lows - but still...most people getting lab tests done are sick.
Were the tests done at the same time of the day. testosterone drops off in the afternoon - and after certain stresses like not enough sleep. If you did one test in the morning and one in the afternoon you would (not could) get 2 markedly different readings. My blood testo when off is typically over 900 at 7:30 AM, and is in the 400's by 3:00 PM.
Testosterone fluctuates and can fluctuate markedly depending on diet (alcohol increases estrogen and lowers testosterone), sleep patterns, time of day, how much sex you are having, etc.
I did compare salivary and blood IGF-1 tests once - took the salivary reading on the way to the lab (takes like 20 minutes to collect enough spit), hopped out of the car had the blood test done, hopped in the car and drove to the post office and mailed the spit kit. They were comparable. Tests done a month apart - especially if you took avena, maca, tribulus, prohormones, hit the pussy alot, changed sleep patterns, etc could alter the readings 100%