Had a similar issue on my 07 Gti. ESP and ABS light coming on intermittently and reset by an engine start, but it never went into 'limp mode'.
Got a friend to scan it with VDCS, nothing conclusive, but read an error on the nearside rear ABS sensor. After reading a number of threads etc the most common cause was the ABS sensor ring on the bearing itself...fitted a new one and all was good and has been ever since.
From my research on this, it was either the ABS sensor, the sensor ring on the bearing or very rarely the sensor inside the ABS pump. Hopefully not the later as thats an expensive part to replace, although I believe VW have a 'fix kit' for it rather than replacing the whole unit.