SOC randomly jumping to 100%

I did not set up my system but I am slowly learning about it so please bear with me for any silly questions. I have Batrium BMS and Victoron inverter and MMPT.

I have recently had several issues where my SOC has randonly jumped to 99%, both times were overnight. I have not been able to identify the cause of this issue and wondered if anyone else had experienced similar problems. I have manually reset the SOC to what it was when it jumped but I am also concerened that now it isn’t quite correct?

The person I bought the boat off that set up the system has been some help and has reassured me that this is ok and the SOC will balance itself over time. Is this correct and an I test if in some way?