You probably didn't get a completely even application of paste. There may be a spot closest to that core that is hotter where you got too much or too little coverage, or an air bubble. You can try to reapply the paste, but honestly, so long as as the hottest core is below 80°C under a FULL load running Prime95 version 26.6 (ONLY, no other version) then it probably isn't worth bothering with to do it over again. Variance between cores is normal and so long as it is below ten degrees variance from hottest to coolest core temp, you are within allowable tolerance.
If you KNOW for sure it was less than what you are seeing now, before, then trying again might be worth doing.
Arctic silver 5 is ok, fine actually, but both Noctua NT-H2 and Thermal grizzly Kryonaut are considerably better. By considerably, I mean about 3-5°C peak.
Looking at your screenshots, I only see a maximum of about two degrees difference between highest to lowest core. Not sure where you are seeing a five degree variance. Keep in mind, idle is irrelevant. Run Prime95 version 26.6, and take those same screenshots again of the core temps after about five minutes. Do not run newer versions than 26.6, that use AVX instructions. They are not steady state and they create unrealistic thermal conditions.