Engadget:

Last month, MoviePass CEO Mitch Lowe announced that surge pricing would soon go into effect, charging customers a little extra for movies and showtimes that are especially popular. That added fee, which MoviePass is calling Peak Pricing, starts rolling out today to customers with a monthly plan as well as any new annual subscribers. When a film or a particular showtime is in high demand and subject to an additional fee, you'll see a little red lightning icon over the showtime. Any showtimes that are gaining in popularity and could have an added Peak Pricing fee soon will have a grey lightning icon above them.

Per the screenshots shown, it looks like the peak pricing fees won’t be too high ($3.43?), but we’ll have to see how things change over time.

I will say that this fits in more with MoviePass’s original pitch to exhibitors of trying to get people in during slower periods of time/less attended screenings.