It never is wrong to ask questions. Yes some may seem simplistic to some people. The same people may ask a question to seems simplistic to others. One can never stop learning though.
However, the good thing about Deans I have found, and some of the reputable companies is if it did not work, they will keep treating it until it is corrected. The bad thing is the repeated calls and trips to get it fixed.
The last time I had a problem in the grass, Deans put in a follow up visit in their system to check it and keep treating it. Since it is outside, you are not inconvenienced by their visits. It's the inside ones with the 2-4 hour windows that are annoying.