Yep Gill, Remus does this on lead and off. Head down, shoulders hunkered up, ears forward. He doesn't lay down though, keeps walking - then waits until he's within striking distance and launches himself like a missile towards the other dog, wanting to play
Dogs that know us are fine with this exhuberant approach but for small dogs or any that don't know he's friendly, I always put him back on-lead and use the Leave it command. 40 kg of GSD tearing towards you is far from ideal

It's the one thing I really struggle to train out of him. So any suggestions from those that have achieved this please send me a PM!