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.
We started with monthly €1,300/founder. Today, we're paying us €2.500/founder.
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.