Here’s a shot from the start of the film roll.

Here’s one about 6 frames in, taken a day later.

A similar thing happened with a roll that sat for a couple of years (!) from the first shot taken, to eventual development a few weeks ago. One of the first frames:

A shot from the end of the roll (note that the blurriness here isn’t grain, it’s camera shake because I accidentally switched the Holga to bulb mode):

A (slightly less expired) roll of black and white had the opposite progression. Here’s a shot taken last November:

Followed by one shot in January:

My theory about the color film is that the outer layers of the roll, which are used first, had more exposure to heat and thus more color effects. I don’t know why the black and white roll seems to get grainier toward the end, though. It only sat in the camera for a couple of months, and wasn’t exposed to any extreme temperature changes in the meantime. Just a fluke, perhaps?