That sounds like it might have been a one-time bug, unless they fixed it. I did a level just now with no space, but the game still prompted me to buy one.
EDIT: A side note as well, a really nice QoL change for the future would be, being able to see what rewards a date level can give AFTER you've used all your original attempts on it. Otherwise you wouldn't want to reset your attempts because you don't remember what drops in each level.