I haven't run across this with anyone but empaths, but if you make a typo and thus end up not actually casting a healing spell, it acts as if you've actually cast a spell, in terms of it won't allow you a "doover".
Example:
>cast right arm'
You gesture.
What are you trying to cast at? The syntax for casting healing spells is "CAST [RIGHT|LEFT] <body part>."
>
A worker enters pushing a wheelbarrow. He dumps everything in the hollow into his wheelbarrow and begins to pick through the items....
Having found nothing of interest to keep or save, he leaves again.
>
You feel fully rested.
>cast right arm
You don't have a spell prepared!
<<The real thing DR needs is to get out there to the kids who actually read books.>>