Mysterious Credit Balance on SMETS2 gas meter

I pay by regular direct debit and get monthly statements showing my usage. When I press Button A on my Landis and Gyr SMETS2 gas meter I get the meter index in cubic metres. On giving it a second press a “Credit Balance” in £s is shown as if I were a pre-payment customer. Can anyone explain what this is and where the figure came from? (it’s a bit less than £30). I should perhaps add that remotely obtained smart meter reads are not yet making it as far as my statements which are still being based on estimates. I have informed Bulb.

I might also add that I do happen to currently have a credit balance on my Bulb account but it isn’t the same amount and it isn’t just for gas so why would it appear on my gas meter anyway? I find it completely baffling.

It has got worse - the balance shown is down to just over £5. The big question is will the meter shut my gas off when it reaches zero?

Bulb have helpfully explained that the balance shown on the meter screen is the cost so far for the current billing period and does not mean the meter is in prepayment mode. So I think I was wrong to read it as “Credit Bal = £5.21”. More likely it should be read as two statements -“Credit ON” and “Bal = £5.21”.