issues with carbon capture canister switch

I have a 2010 gen 111 with nav system etc, the other day a orange check engine light came on, I took it to our Toyota Dealer and they said that I had mud and gravel????? up in the car, near the fuel intake area?? and that the carbon capture canister/switch was damaged by the dirt and I need to get it replaced. I asked if I could simply not make the repair (which they are quoting me as a $700+ Canadian + labour) due to the fact that the electronics system would eventually not be able to read the H Carbon readings and the car would burn more fuel.
is this a regular problem with this model. I dont do any 4x4 off road running but I live in rural Ontario Canada and do occasionally drive on gravel roads . the service fellow said it wasnt due to my gravel laneway. we are pretty upset by the news about dirt and gravel getting that far up into a system.
any advice or words of comfort? thanks