It is okay to have interesting problems, but sometimes when you are making cheese the problems get way too interesting. In this case, we blame the pea hay.
The farmer made three different batches of cheese, from three different batches of milk, on three different days. Everything looked nice. The cheeses were aged for a while. The farmer went to taste the cheeses. On the outside, fine. On the inside, a surprise. Eyes. More eyes than an elderly potato.
The farmer tasted the cheeses. They all tasted nice, but they all tasted like swiss cheese. Because they were. Because propionic acid bacteria, the culture that gives swiss cheese its eyes and some of its characteristic flavor, had apparently somehow invaded them. That's right, p. shermanii, aka Propionibacterium freudenreichii subsp. shermanii.
Well, how did that happen? We don't have any p. shermanii here since we don't make swiss cheese, since you can't sell swiss cheese at the Farmer's Market, that would be like trying to sell organic Velveeta. A posse of angry epicureans would be on your tail in a heartbeat. They would put on their Neal's Yard Dairy t-shirts and their Herve Mons baseball caps and run you right out of town.
The farmer went to a dark secret corner of the Internet where the cheesebrains (different from cheeseheads) lurk and on bended knee asked the oracles what might be causing the p. shermanii invasion.
First there was silence on the other end, then hypotheses started coming in. It turns out that this is the time of year that the wild propionics begin to emerge, as the animals move onto their winter feed. Some feeds make a better home for the wild propionics, and it turns out that pea hay is much more hospitable to p. shermanii than alfalfa.
Usually we eat alfalfa, but this year we're eating pea hay. It's delicious, I can see why the wild props like to live in it.
Anyway, that seemed to solve the mystery, but not the problem.
The farmer was talking to another much better and smarter cheesemaker and bemoaning the accidental swiss cheese. Who wants to buy farmstead swiss cheese? Swiss cheese comes in sandwich slices in a plastic bag, swinging from the supermarket hooks.
The smart cheesemaker tut-tutted kindly. "Don't be silly. People love swiss cheese. You just can't call it swiss cheese. You have to call it Gruyere."
Ah, of course, Gruyere.
Or as they say at Microsoft - that's not a bug, that's a feature.