I was driving my lexus 2001 ls430 this morning and the sunroof opened on its own

 

Gremlins? Perhaps the button was stuck?

Does the sunroof open and close correctly with the button? Was it just a one time event or can you reproduce it?

 

Any rain during this?

 

I had this happen recently in my 01. Not sure if this fixed it but have not had it since. I took the overhead panel with the switches out and took it apart and cleaned the contacts on the switches and cables. Might want to start there and see if it helpsl

 

You sure you didn't provoke it? The sunroof is well-behaved until you've pushed it's buttons then all bets are off.