Might be the case - I'm looking at the warranty booklet on the Acura site and the pages that are supposed to describe any "extended" coverage for emissions components (including hybrid powertrain) are missing.

The Hybrid system has a lot of components with longer warranty. It's located on the last page of my warranty book... ( I tried a cut and paste below but it all ran together, just check your warranty book).

Federal and California Emissions Warranties Parts List
BPL04916 (1701)
00X31-TRX-W000 2017 MDX Sport Hybrid
Emissions warranties are state specific. Refer to the years/miles1 columns below as follows: • A – Minimum coverage for all vehicles in all states • B – Vehicles registered and normally operated in California, Connecticut, Delaware, Maine, Maryland, Massachusetts, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Vermont, and Washington
System Covered/Part Name A B Evaporative and Refueling Emissions Control System Fuel Tank (including Fuel Tank Vapor Control Valve and Vapor Recirculation Tube) 4/50 7/70 Fuel Pressure Regulator 4/50 7/70 Fuel Filter2 4/50 7/70 Fuel Filler Neck Restrictor 4/50 7/70 Exhaust System Catalytic Converters 8/80 8/80 Fuel Injection System Engine/Powertrain Control Module (including Barometric Pressure Sensor and Software Upgrades) 8/80 8/80 Fuel Rails 4/50 7/70 OBD System Data Link Connector (DLC) 4/50 7/70 Malfunction Indicator Lamp (MIL) 4/50 7/70 Transmission Control System Transmission Control Module (including software upgrades) 8/80 8/80 Actuator Assembly 4/50 7/70
System Covered/Part Name A B Intake Air System Intake Manifold Assembly 4/50 7/70 Valve Control System Rocker Arm Control Valve Assembly 4/50 7/70 Hybrid System Battery Assembly (including all internal components) 8/100 8/100 Motor Control Module (including software upgrades) 8/100 8/100 Motor Power Inverter Module (including all internal components) 8/100 8/100 Motor Rotor 8/100 8/100 Motor Stator 8/100 8/100 Electric Motor Control Module Coolant Pump Relay 4/50 7/70 Motor Control Module Relay 4/50 7/70 Battery Module Fuse 4/50 7/70 Battery Module Fan Relay 4/50 7/70 Bypass Contactor and Resistor 4/50 7/70 Battery Condition Monitor Module 4/50 7/70 High Voltage Contactor 4/50 7/70 Motor Power Cable 4/50 7/70
Federal and California Emissions Warranties Parts List
BPL04916 (1701)
00X31-TRX-W000 2017 MDX Sport Hybrid
System Covered/Part Name A B Hybrid System (cont.) High Voltage Motor Power Inverter Module Cable 4/50 7/70 Hybrid System Relays 4/50 7/70
Miscellaneous Parts that are used in conjunction with the items in this list are covered. Some examples are clamps, brackets, piping, nuts, bolts, fasteners, switches, sensors, solenoids, wires, harnesses, connectors, seals, software updates, and gaskets. 1 Coverage in years or 1,000 miles, whichever comes first. 2 Fuel filter replacement and fuel tank flushing are covered when contamination results from a defect in material or workmanship.

I have owned 2018 Sport Hybrid for 2 weeks now and I have noticed none of that.