Weird game crash

Been in game a while today leveling in Classic. Flying commercial between Theramore and Darnassus and WoW crashes. Screen turned all white then window popped up saying “not enough memory… (something)” then another window asking to report what I was doing in game when the game crashed. When I clicked to log back on, I got this pop up. “Your 3D accelerator card is not supported by World of Warcraft. Please install a 3D accelerator card with dual-TMU support.” I closed the launcher and restarted my computer and am now back in game and my toon was still flying to darnassus. I have no idea what that meant, I’m an older chick and am not very tech oriented. Is this the precursor of a big problem or just a glitch?