Good for you for being in the habit of checking your bike before each ride. Tires get old and brittle and have thread separation. Probably depends on ozone and uv exposure and maybe road grime/chemicals. But some rubber compounds have better longevity than other.

Where are the cracks in your rim? Are they where the spoke nipples attach, or on the sidewalls? Sidewalls do wear thin from braking, faster on sandy roads. Cracks near the nipples would indicate excess spoke tension beyond what the rim could bear. Low spoke-count wheels need higher tension and may fail sooner. How old are your wheels? Good your LBS is honoring the warranty.