Yes, of course: the biggest factor are our salaries – we're raising them steadily as we're making more money. The second (minor) factor is that some costs are rising depending on the number of customers/users, such as payment or server costs.
That said, I really really really like the design of the site. Insanely so. The home page is sublime, and the 'Tour' page is near perfection. Grats and good luck.
We started with monthly €1,300/founder. Today, we're paying us €2.500/founder.