The "something stupid" is that the landlord turns around and says "never mind" and says we don't have a lease.

That would suck because it leaves us in a position where we signed, paid and have keys but are being told to hold off and thus are losing days in the month that we have paid for. If we try to offset that by moving in we risk being told we broke in before we had full permission.

Technically the landlord could hold off on giving us the go for months while meeting his obligation of signing the lease and giving us keys. Meaning we have money sitting in his hands not working for us. If we acted on it through some legal channel he can just say "hey, they had the keys." It's just a weird up in the air situation that I prefer not to be in as I've already had one landlord get cold feet and accuse us of a break in after we gave money and got keys and permission to move in.

In this case we got signage, keys, paid but are being told we can't move in.

Note: We actually have moved in and got it resolved at this point via our agent but I'm still curious as to my original question.