A note on the integrality of mirror maps

We give a class of examples of $A$-hypergeometric systems that display integrality of mirror maps. Specifically, these systems have solutions $F(\lambda_1,\dots,\lambda_N) = 1$ and $\log\lambda^l + G(\lambda_1,\dots,\lambda_N)$ (for certain $l\in{\mathbb Z}^N$) such that $\exp G(\lambda)$ has integral coefficients. The proof requires only some elementary congruences.