Should I say something?

[matelot]

if you think the tree is going to fall on a road I would email the local council highways department. let the council decide if it's dangerous or not.

 

I'd keep a record of the email.

[adam pike]

I would drop in and explain you are not bitter about not getting the work but feel that the works that have been done has made the tree unsafe and tell them to make sure that the other contractor is also aware of this. At least then if the tree does fall down into the road and hurt someone your conscience is clear that you have done everything in your power to inform them of all the information