Yes it's possible to get a rogue reading with a finger prick test, could be a faulty strip or just the accuracy of the machines.
If you get a reading you don't expect, high or low it pays to double check by repeating the test.
Remember our testing methods are not as accurate as we would like. The manufacturing standards for accuracy are +/- 15% for 95% of the tests.
If you look at the table here
https://www.diabetes.co.uk/blood-glucose-meters/blood-glucose-meter-accuracy.html you will see that even with the newer improved standards,
A reading of 3.5 means your actual level is somewhere between 2.67 and 4.33 .
When you take this into account your previous lowest of 3.9 and this 3.2 are both within this 15%. which means both results were in the same ball park
And remember this is for 95% of the tests, which means that 1 in 20 results could be outside of even the 15%.
Personally I think you did the right thing treating a possible hypo even if you didn't feel it, better to be safe than sorry.