Insulin leaks from your reservoir or infusion set are usually so small they are quite hard to detect. Your pump will not warn you of leaks. Insulin has a distinctive smell, often describes as creosote, or railroad ties, or Band-Aids. Regular blood sugar tests are the only reliable way to detect leaks. No warning except for high blood sugars!
A hub will leak when it is not tightened snugly, but may also crack if tightened too much (Makes a thin crack down the hub that is hard to see).
Tighten hubs firmly but carefully at pump setup. If a leak is suspected, smell the hub for insulin. Insulin usually dries fast and cannot be seen. Replace the reservoir and infusion line if you are unsure about a hub leak.