Did'nt happened till now for a second time. I have checked oil level and I found near a cup of tea of extra fluid inside (@ 41 degree c). I found this on the Internet too
Make : BMW Model : X3 Year : 2005 Manufacturer : BMW of North America, LLC Service Bulletin Number : SIB-24-05-06 Date of Bulletin : DEC 01, 2009 NHTSA Item Number : 10033133 Component : POWER TRAIN:AUTOMATIC TRANSMISSION Summary :
BMW VEHICLES: DELAYED UPSHIFT MAY OCCUR UPHILL IN 3RD OR 4TH GEAR. THE TRANSMISSION WILL NOT UPSHIFT, USUALLY AFTER GOING UP A SLIGHT INCLINE, AND STAYS IN EITHER 3RD OR 4TH GEAR TOO LONG. CALIBRATON SENSITIVITY IN THE HILL RECOGNITION PROGRAM OF THE EGS TRANSMISSION MODULE. MODELS E83, X3. NO MODEL YEARS LISTED. *PEwell it happened when I was going up on a slightly inclined road. might be this the cause? or that overfill ?