Yes, in #689 1st. Also "sylphs" multiple times, as well as "cryptkeeper", and "scryproof". I didn't count any of these because the "y" in those words is clearly a vowel. There are some borderline ones in Haley's encrypted speech where I'm not sure if the "y" is a vowel or not and just made a subjective decision, like "qxyklkbe" and "lduzrycyrv".
Update: oh yes, Ruck has a good point, #689 actually says "rythym". Funny misspelling. I assume most of these typos are fixed in the book version, but in this thread we only care about the online version of the strips.