If you didn't need a new belt before you probably do now - the Kevlar and polyurethane micro-V belt will last pretty much for ever - there is no set replacement period, our local Honda service manager told me his had done 120,000 miles and still OK, they only replace if badly cracked or frayed.
Your belt probably just needed a small adjustment. They cost about £50 from dealer for belt, don't know what they charge for fitting, they obviously don't get much demand for new belts as last time I tried to buy one they said they don't keep in stock and would have to order it in, that is when tech told me about his car, so I did not replace my belt as it looked OK and was still OK when I traded car in at over 120,000 miles.
But WD-40 on the belt wont do any good as belt relies on friction to work, its a bit like spraying it on your brakes or clutch plate.
There is a deflection idling roller on belt, sometimes if bearing gives up it can squeak.