Yes
(Better late than never for this post)
Back when I was still in the Army (60's), I was serving as a microwave radio repairman (telephone exchange) out of San Antonio TX. At the time as a part of my duties I had the added task of installing intercom and public address systems. I was called to the base commandant's office and was told to report to the base helo pad. When I arrived the president's helo was awaiting me to transport me to the president's ranch.
In case you haven't figured it out yet, the president at the time was LBJ. For those who have forgotten - that's Lyndon Baines Johnson. On the first of two trips LBJ was not present. On the second trip after needed equipment and supplies (public address system) were obtained, I and a co-worker along with all of the requisitioned equipment and supplies were transported to LBJ's ranch.
After landing, myself and my partner were offloading all of our 'baggage' when I dropped a box of speaker wire and a box of terminals. I spotted what I thought was a ranch hand standing by a barn with his back turned towards me. Since I had both hands full I hollered at him and asked if he could lend a hand by picking up the dropped boxes and placing them on the stack I was carrying.
You never saw such immediate reaction. Secret service agents were coming out of the woodwork. You see, the ranch hand was LBJ himself.
So yes - I have met a president.
Oh by the way, LBJ did pick up the boxes and placed them atop the stack I was carrying.