I have no saves close enough. I played through again from an earlier save, but of course the AI did something else. Other units in that game did exactly the same though - routed or retreated when it seemed surprising. I doubt it's a bug, in the sense I suspect the game is set up to allow this, but I do think I agree with Wodin that - in the circs above - a retreat might be believable, but not a rout. A rout is chaos, fleeing full speed without order. I notice that the experience of the unit isn't super, but I had a look at the D-40 and was surprised to se its stats were like this;
these are the stats it starts the scenario with. Not so much better than the unit it routs, if at all.
plus, it's not Shermans at all!!!!! It's bloody Stuarts. So that makes me think it's even more bizarre. It's a wonder they took out a Panther at all, let alone got a company to rout.
I surrendered shortly after - to check the position - and found the D-40 was also, in fact, routing!!! They're both fleeing each other in total chaos. Does that make it better or worse, I wonder? Maybe more believable. But I have a problem with 6 stuarts routing 11 panthers. At the time the intel was they were shermans, i admit, but even so....Given the facings (my units offering no rear ends - at best offering a side shot) is it possible that a Stuart would take out a panther?