X5 Gearbox advice

[mateus]

Had a strange occurance tonight, reversed out of a parking space, shifted to drive and no drive engaged, then suddenly engaged and wheel spun. After this seemed to stay in 3rd?.

I struggled home as it was pissing with rain rather than stop and take a look. When I got home I turned of the engine selected park restarted and reversed for 10 ft to see if it would re engage? selected drive and then it was OK???

Any clues ? or is this the first of impending gearbox problem.....

Car was serviced 1300 miles ago all levels fine.