+1 with dogmama. Get a written statement from the animal control officer to the effect of what he said, "Looks like a scratch not a bite". Get things in order for a strong defense and sit tight with the information.

Just laying low will not cut it. Like Irulan said, some people do not like animals!! Hiding is no defense should someone decides to pursue legal recourse. That scratch can turn into serious condition for an elderly person. A scratch can turn into a long lasting oozing wound.

I'm not trying to scare you Emily, but I would err on side of caution. Getting the certification sounds like a good thing too. Geeze, I can just see.

How did you get the wound on your arm?
That vicious dog attacked me without provacation!
The VICIOUS DOG ATTACKED YOU?
Yes Sir
But there is a certification saying otherwise. Do you still wish to claim that the dog is vicious?
....

I think having the certification after the fact is still very relevant and getting ASAP would be much better than later.