Hd sentinel log report errors, performance dropped to 98%

[Gondar]

Yesterday i connected external usb hdd and hd sentinel shows some errors, and performance first dropped to 99%, and then to 98%. HDD passed self test, and after i clear log performance has come back to 100%. I rarely used hdd, kept it well in good temperature, no moisture etc. Model is SP armor a80, here are the screenshots: