Question: Why does Maple put a strange set of variables in my output? (Physics)

I was unsure if this should be a post or a question, or how to word it properly as I feel the attached file is the best way to see my issue. 

 However, when doing a computation involing the D_ specifically D_[mu](F[~mu,~nu]) where F is a tensor, Maple is putting in strange "variables" into the output of my expression. I set the spacetime variables myself to tau,x,y,z and in the output there is combinations which appear as x(tau),y(tau) which has completely baffled me. 

Any ideas/help would be greatly appreciated. 

EinsteinPert.mw

EDIT: The problem is resolved when the Physics[Vectors] package is removed and replaced by VectorCalculus for the Lapacian. Still curious as why the Physics[Vectors] package causes this issue. (I of course could just brute force the Laplacian but I thought I would use the power of Maple for this).