Slight cell variations are normal, especially for an aging battery. Variation within 0.05V after a balance charge is normal for a battery.
Cell manufacturers acknowledge these variations when they go though their quality control, allowing for slight acceptable capacity variation. Then over time cell drift will make these variations move and settle over time. These variations are generally insignificant and reflect an aging battery.
Larger variations then standard can be indicative of a battery with damaged welds, faulty cells, faulty BMS, faulty charger, etc. If your battery has large variations in cell levels, please contact our support team.