You ask "Is it a matter of concern..."

NO!

There are a lot of factors that go into PSA results as others have said:

The lab - which assay they use, calibration of their equipment...
Your pre-lab routine

Attached is my clinical history. When my medical team switched from the traditional single decimal point to the USPA, two decimal point, there were variations as you can see in my clinical history (attached).

So, what you are looking for is multiple PSA tests, spaced some time apart, that show a continuous and upward trend. What that time interval is for spacing of the labs is something to discuss with your medical team. For me and mine, it was 2-4 months, three or more tests and a PSA between .5-1, giving us an almost 2/3 chance of imaging locating where the PCa was, thus informing the treatment decision.

The switch from the standard PSA to USPA has been a blessing and a curse. It brings prostate specific anxiety to a new level where every "change" is scrutinized by us, the patient for significance. Keep in mind, even if the change in PSA is indicative of a return, there are other clinical factors in play:

Gleason Score
Grade Group
PSADT
PSAV
Imaging.

Also, if you were on the standard test, which many still do, your results would be < .1 and you and your medical team would be spending the consult time talking about other things, vacations, best places to dine out, the concert you went to, kids...

Relax..

Kevin