The position in question has been called weak agnosticism (also "soft", "open", "empirical", or "temporal agnosticism"). Here are the relevant definitions from Wikipedia.
Strong agnosticism (also called "hard", "closed", "strict", or "permanent agnosticism")
The view that the question of the existence or nonexistence of a deity or deities, and the nature of ultimate reality is unknowable by reason of our natural inability to verify any experience with anything but another subjective experience. A strong agnostic would say, "I cannot know whether a deity exists or not, and neither can you."
Weak agnosticism (also called "soft", "open", "empirical", or "temporal agnosticism")
The view that the existence or nonexistence of any deities is currently unknown but is not necessarily unknowable; therefore, one will withhold judgment until evidence, if any, becomes available. A weak agnostic would say, "I don't know whether any deities exist or not, but maybe one day, if there is evidence, we can find something out."