Yes not too worried about my score per se, Im sure its great as I have always paid all my bills on time and always paid my credit cards off in full every month.
But the amount of credit you already have is one thing providers use to determine how well you can service any new potential debt (strikes me strange they don't differentiate between those who pay interest vs those that pay off in full). So logic says if I currently have 3 CCs, each with a 15-20K credit limit, cancelling one of those before applying for a new one with same credit limit, would leave my ability to service payments the same make decision a no brainer, vs increasing total credit.