I have a pb changing a 64Mo CompactFlash to a 128Mo:
My STPC-embedded application mounts the CompactFlash in the .build script like this:
devb-eide nobmstr blk alloc=512k cache=512k automount=hd0t77:/hd &
After boot, I can do a dinit on /hd:
dinit /dev/hd0t77
→ Disk ‘/dev/hd0t77’ contains xxx blocks (yyyK) → OK !
After changing 64Mo Flash to 128Mo Flash, then reboot:
dinit /dev/hd0t77 says I must use -h option.
WHY IS THERE A DIFFERENCE ?
I am surprised that you didn’t need the -h the first time as well. That is the normal behaviour. For some reason dinit didn’t think the flash (in the first case) was a hard disk.
It is possible that what dinit uses is the flag to see if it is removable media, and yuor first compact flash was reported as removable, and the second wasn’t.
In the end, as I mentioned, the second behaviour is what I would expect, so unless there is another concern, don’t worry about it. 
Rick…