No one will know what their criteria are. It's their money that they're lending so they make up the rules as to who they will lend to.

Your bank knows your financial sutuation much better than any other lender, so that's probably why you got a great rate from them.

I wouldn't worry about it. I've been rejected for a CC in the past despite there being nothing out of the ordinary. Applied elsewhere a couple of days later and got a 5 figure limit with a fantastic rate (not that I pay interest on CC's!)