I forgot the make my credit card payment yesterday. I feel so bad because I told myself all day yesterday not to forget.
Was the due date yesterday?  Is the payment late now?  
I think so. I am feel so guilty because the interest was so avoidable. I forget so many things all the time...
Sometimes there is actually a grace period after the due date.  I've paid bills a couple of days late without a fee (not sure about credit card interest, though).
You might be right, I'll look into this. Thank you.