Adding to this: Smoke Screen now acts an attack ground command. The 30 munitions is consumed and the ability is 'active' until you move the Sherman. Both the M4A3 and M4A3(76).
I'm not sure if this is a bug or if it's always been like this. With the recent Mechanized Company changes I've been playing with (and loving) the flexibility of the company and USF as a whole.
Now, the M3 half track vehicle doesn't retain its veterancy if the crew gets out to repair. For Vet 2 and 3 crews this isn't an issue. Only seems to affect crews getting to Vet 1.
It's appears the M3 half track actually vets faster than the crew. I guess it's not much of an issue as the vehicle gains veterancy quickly. However, having the 'Step on it!' ability continuously locked again until the crew reaches Vet 1 is a pain in the ass.