Depends on what they've used. 99% of herbicides used residentially are labeled safe after dried. Ask them to give you the product name and active ingredients., you can ask me if you want. Unfortunately, working with (not since DD however) herbicides, is a large part of my job.
If your a.i. is:
2,4-D amine (salt)
then I wouldn't worry.
If you'd like to educate yourself on herbicdes (or anyone for that matter), here is a great link. I am not condoning or encouraging the use of chemicals. I just feel more comofrtable knowing how they work, tox levels, and when/where their use is warranted.http://tncweeds.ucdavis.edu/products...icideTable.pdf
I still can't believe that they sprayed when you said not too. I would contact a supervisor of the company. That is a big no-no and huge liability on their part.
FYI, appx. 16 states have sort form of law requiring advance notification (even on public right-of-ways) before spraying pesticides/herbicides if you are registered on a list. Maine as an examplehttp://www.maine.gov/agriculture/pes...c/registry.htm
The laws vary, most cover at least public spraying. It might be worth checking into - you can check with your state dept of ag regarding this.
Our state does not have a registry. However, citizens can call and request to not spray on the ROW in front of their house. We ask them to post a reminder sign on the prop in the month the area is to be sprayed. In return, we also request they control plant growth in that area.