Hmmm , i remember last summer here once or twice in traffic my 6 did the same thing .
It has not done it since and i put it down to dodgy fuel .
Good to hear it was the RCM , probably shows its fault in the heat . ( it was a stinkin hot day when my CPS failed , in the middle of fing nowhere ..)
I have a brand new RCM i carry in the trunk ...and spare CPS !