You have a good eye and this is a good question.
That growth is not a good sign, and the tree is in fact failing and should be removed, sooner rather than later.
It looks like an ash variety, which makes sense as ash throughout Maryland are being wiped out by the invasive Emerald Ash Borer.
Once the ash dies, it's wood weakens quickly and structural integrity is affected to such an extent that some tree companies charge a hazard rate to climb and remove them. For that reason we suggest having it removed soon.
Here is our page on Emerald Ash Borer:http://extension.umd.edu/hgic/invasives/emerald-ash-borer
and here is a page that helps homeowners decide when to remove a tree: https://extension.umd.edu/learn/how-do-you-decide-when-remove-tree