Surprises on the road are always scary! The instance you’re describing is called “lane splitting” and it refers to motorcyclists cutting through traffic jams or stop-and-go traffic by traveling between two cars instead of in a lane. Is lane splitting legal in Mississippi? The answer is not really, but it’s not exactly outlawed, either.
It’s up to the discretion of law enforcement officers to decide whether or not a motorcyclist is driving recklessly by lane splitting. It’s a risky behavior because drivers, much like in your situation, aren’t expecting for a motorcyclist to pop up next to them. Lane splitting increases the chance of a motorcyclist being hit by a motorist.