Your usage is quite acceptable. Refer to "Webster's Dictionary of English Usage," which states that when using the word verbal to mean oral, "the context almost always makes the meaning clear, and the only serious confusion appears to be in the minds of the commentators themselves...do not let anyone tell you that the use of verbal to mean `oral' is a recent corruption of the language. That idea is a popular myth, nothing more."
I hate to pick on such ticky-tack trivialities, but why not when others do it so well?
Copywriter, Hales Allen Inc.