[Background: the question author (Michael) answered their own question]
Why is this not the accepted answer - waiting for a better one? – piiperi
@piiperi To me, it feels a bit arrogant to accept a self-answered questions before a couple of days have passed. Granted, on the other hand, in the case of this question, a different answer is quite unlikely. – Michael Karcher
I see your NOP (90h), and raise you an explicit DS prefix (3Eh). It's all about the style points! :-) Any instruction with a memory operand can have a segment prefix. In this case, the DS prefix is implicit/implied, but it can be explicitly specified without changing the meaning of the instruction. Both ways work to pad the extra leftover byte of space, but the explicit DS prefix does not change the instruction's execution speed, whereas the NOP actually takes 1 cycle of time to execute (plus possible decoding). – Cody Gray