Full circle

Because I have a company car I have a fuel card.
I’ve been using the same card probably twice a week since August.
Last Thursday I needed to get fuel and on the way to petrol station I realised I no longer recalled the PIN number. That’s crazy.
I put in two numbers I thought might be right - 7743 - no. 7745 - no.
How can this be happening?
Today I needed more fuel so tried more numbers and ended up being locked out so once again had to pay with my debit card.
And then on the way home the number just came to me - 4471.
But it’s too late. The card is locked and I have to request a new one.
I think I’m going senile.