Turns out its not the Smart Top. Happened again when its cold. Thinking about it, it was cold when I was having the problem with the smarttop installed.
Brakes and fule seem to be fine. Likely a bad sensor. Have to take it to the dealer, will probably wait a month till I have more time
2009 Z4 sDrive30i and a 2004 Toyota Land Cruiser - Lifted, locked and a few other toys