4x4 light solid on 1999 5.4 Ford Expedition?

My mother in law started my truck to leave work today, and called saying the 4x4 light was on, as well as the LOW light and felt like it was "caught between gears or something." I told her to turn it off, and back on and see what it does. She did, and the lights went off and it drove normally without any issues. I drove around the block to make sure it wasn't in 4x4, and it wasn't. No lights indicating 4x4 were on, shifted and drove normally. The awd also worked correctly, like it always has. What would cause this one time occurance? Is there possibly a sensor going bad? I would blame it on the faulty clusters in these models, but she physically felt the truck being sluggish and running strangely.

What the heck you doing letting her drive the truck? Should be fine some one probably hit the button by mistake

Yep, it's gonna feels sluggish… In 4-wheel LO, you engage a transfer case gearset that doubles the torque multiplication… It would take double the RPM to drive the same speed. The button is awfully close to the shifter and she probably bumped it all the way to the left and 4-LO by reaching for the gear selector lever. Most likely no harm, no foul.