Again! He did the same thing last year during the campaign. It's on purpose, but for what purpose I don't know.
I recall the same thing...
IMHO, he plays fast and loose with everything. He could be worried about veterans who are Oath Keepers. The recently withdrawn Homeland Security advisory about veterans being potential right wing terrorists comes to mind. They know how the majority of the active duty military and veterans vote.
The Oath, per se, has no expiration date, just the service agreement.