Pressure question for a China Vevor HY clone?

I think I have my Vevor compressor lined out, (I Think ?) . Ok my biggest problem was it kicking off to soon. Hollow point suggested
updating the pressure safety switch to 15 amp. WORKED! I,m just filling my Hatsan Flash to 3000 psi. But we know this compressor
is rated to 4500 psi. Now it comes with a test plug to check it out. I,m kind of gun shy even thow I do not need that much pressure.

I only have one extra blow out disk that came with it. But I put the pressure testing plug in it to see if it indeed pumped up to 4500 psi.
I turned on the compressor with the plug in the fill line. Closed the valve & the pressure climbed fast to 3300 psi then just seemed to
stop. I released pressure in the line & turned it off. Question to you guys that know. Is it normal for it to do that when it hits higher pressure? I,m thinking
if I would have not stopped & the compressor may have continued to clime slowly to the 4500 psi. With only one blow out disk I did not want
to chance it. I assume E-bay has extra blow out disk. Your thought Please. 

Fly