Andrew peacock

Hi, I have a 2007 XJ 2.7 diesel with 50,000 miles, during the summer I had a full service including gearbox oil and filter change, the last couple of days the temperature has fallen and when I start off in the morning the gearbox fault comes on the dash and it stays in 3rd gear, when it gets up to temperature I switch off and restart and all is fine for the rest of the day. has anyone experienced the same problem ? Please help! Andy.