It's not misbranding as long as you're 100% factual. Remember that "
510k clearance" is factually a SE determination - no more, no less.
The FDA is not fond of manufacturers trying to leverage their regulatory position for marketing gain. Specifically, they might come down hard on you if you try to hint or suggest that the device is in any way "approved by the FDA" (unless you have a PMA, which is exactly that - approval).