Yeah. Calling something a five-sigma event loses meaning if there haven't been anywhere near enough time intervals (here: market days) to validate that thesis.
Not just that, you have to define the independent units. A 1 in 35M event is crazy over 35M days. It's less crazy over 35M trades. Without knowing which it is, 1 in 35M doesn't say anything.
Here is a decent paper on the topic of n-sigma events: https://arxiv.org/pdf/1103.5672.pdf