I had a "check charging system" light on my 11 MDX when I purchased used back in 14. The dealership did a firmware update and that corrected the issue. The only other time I got a warning was when my OEM battery was slowly giving out after 4 years in the vehicle. Replaced it with Interstate and zero warning in +5 years.
You might have to take it in to check your cables for corrosion, load test battery if you are +4 years, alternator output voltage, and ground wires.
Dad - 19 MDX Sport Hybrid Adv Fathom Blue Pearl w/ Graystone
Mom - 18 RLX Sport Hybrid Brilliant Red Metallic w/ Ebony
06 TSX w/ Navi (Totaled Oct/19), 08 RDX Tech (Daughter), 11 MDX Adv/Ent