Do I need to explain large withdrawals from PoF account?

[northern sunshine]

I have one bank account that I'm using as my settlement funds for my PR application and meet the minimum funds required. However, in the past 6 months I transferred out a large sum into a certificate of deposit, so it is visible in my statements, but I still left enough funds in the account for PoF. Do I need to explain that transaction in a LoE? Do they care about large money transfers out of the account?

Thanks.