Truffles in a greenhouse

I have never heard of this problem and I guess it isn't a problem but has anyone heard of this before. A neighbor a few acres away has a greenhouse. She uses that ugly green astro turf carpet as a walkway/weeed barrier in her greenhouse. She rolls up the walkways and hoses them off after a season outside the greenhouse. For the last two seasons she has had truffles grow under the carpet. They don't grow anywhere else in the greenhouse just under the carpeted walkway. No special soil in the walkway just the common pumice pine duff that is here.

humidity tends to gather on the walls and ceiling of my greenhouse. Shutting the door is enough to make it fall. I've used black astroturf for the floor.
Regular moisture, warmth, and weed control would offer excellent growth conditions.