As stated... Send them an eMail ASAP.
Most of us have had accidental clicks, but if you inform them, it's all good.
It also sets up a condition of trust between you and them, which may well work to your advantage if you ever get click bombed or some other situation arises.
I keep them informed of just about everything I do...
honesty is the best policy although some will say otherwise.
I dont like suprises, neither does Google.
So if you are creating something new, and it will cause a spike, let them know beforehand... it will pay off in the end the extra time spent.
Peace,
Cy