Rule 240 states that an airline must deliver you to your destination within two hours of the originally scheduled flight time. If they cannot, they must put you on another carrier.
Rule 240 does not apply to weather-related delays: only mechanical delays, or delays that are completely the fault of the airline. The following are NOT the fault of the airline (known as a Force Majeure Events):
weather, acts of God, riots, civil commotion, embargoes, wars, hostilities, disturbances, unsettled international conditions, and any strike, work stoppage, slowdown, lockout or any other labor-related dispute involving or affecting the airline's service, etc.
If there's a Force Majeure Event, the airlines only obligation is to refund your ticket. Airlines will typically do their best to get you to your destination, but they're not necessarily obligated to do so.
A 5 minute schedule change is not sufficent to warranty a refund.