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I recommend to you to use the resonance method, it’s more accurate. You are using a very simple VNA and there are errors of measurement bigger than the magnitude or real part of Z. I posted a method based on VNA that would be more accurate and repeatable. If you would like to measure the Q on several frequencies you can use a variable capacitor..
Figure that NanoVNA can measure resistor in a range of 50Ω there are no specifications for this instrument but for example for a R&S VNA model ZND ( I attached the accuracy plot) the S11 magnitude uncertainty is for Abs(S11) close to 1 is 0.02. Propagating errors it results for your specific case where the imaginary part of Z is 26,88 Ω in a real part error of 0,64 Ω * , and this is a mid range VNA!!
There are also a parasite capacitance on inductor that can affect the measurements.

You can find my post on : Step by step on measuring inductor and self resonance


* I used the appropriate formula :

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Where X is the measured reactance , data gamma is the measurement uncertainty Zo=50Ω

Regards, Patricio.
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