Possible error reading StatusBlockWrapper.Tag?

[rjonkman]

USBHost_t36/MassStorageDriver.cpp

Line 429 in 69b9072

if(StatusBlockWrapper.Tag != CBWTag) return msProcessError(MS_CSW_TAG_ERROR); // Tag mismatch error

StatusBlockWrapper.Tag is initialized to 0, and then is being updated outside of the scope of this function. Isn't there a chance that the code might store StatusBlockWrapper.Tag in a register (with a value of zero). And then later when it checks if(StatusBlockWrapper.Tag != CBWTag) erroneously report an error?