Very strange; I paid slightly below the current minimum price ($5.00), but I still got a Steam key.
OTOH, the soundtrack has gone AWOL (mail already sent).
I just checked a few other games I bought on itch.io during a sale, and nothing seems to have disappeared there - does this perhaps only happen with pay-what-you-want games without a minimum price? (I guess otherwise a bug like ""dev increases price -> items in a user's download page go *POOF*" would long have been noticed...:-))