Am I responsible if artillery fungus develops in my mulch and lands on my neighbors property?

I have a mulched garden bed which seems to have developed artillery fungus at some point. I assume that this is something that just naturally grows and spreads and that the mulched bed became infected at some point.

My neighbor put on new siding a year ago and is finally getting around to painting their house. They discovered the artillery spores (originally thinking it was paint from my house) and this is the first time I’ve heard of them.

Am I responsible for the natural spreading of a fungus?

Location: Washington state