[seL4] memory zero'ing

I'm chasing an issue that looks like retype'd memory has nonsense data. If I read the kernel code correctly it looks like the object returned by an seL4_UntypeRetype syscall should be zero'd (looks to happen when an untyped memory object is reset here https://github.com/seL4/seL4/blob/master/src/object/untyped.c#L254). Is that correct? I don't see anything called out in the manual.

-Sam