I ran my Tiger 1 gearboxes in yesterday straight from the battery. Did them with fine lapping paste for about an hour. Put everything back in with some Triflon, Teflon grease and fitted a grease shield to protect the circuit boards from any flying grease that may come adrift. Turned on and everything sounded great except the motors run backwards

No idea what has happened. Colour for colour the connections have been put back in the correct way.
Just thought I'd ask if anyone has come across this before?

The simple fix is just to swap polarity on the motors and swap the connections round left to right so the steering is right but I would like to figure out whats happened first.