After speaking with the Smithsonian curator of space suits Amanda Young, she confirmed that they are indeed the pants made for Neil Armstrong and they are the earliest serial number Apollo inflight garments known to exist. Previously Walt Cunningham's set was the earliest serial number known and that his set is SN-1005.
The set of inflight garments that Neil wore on the moon, serial number 1038, are in the Smithsonians collection. I purchased this set of pants from the family of the woman who was in charge of cleaning and repairing all of the EVA spacesuits and inflight garments for the Gemini, Apollo and early shuttle astronauts.
My son Dylan wore these pants to school for career day, along with a flight helmet, so he could impress all the 1st grade girls that he was going to be an astronaut. I let him wear the pants for about 1 hour, then I took them home. He asked me why he couldn't keep them on all day, so I told him that he was wearing a years worth of his college fund and if he destroyed them, he'd be going to plumbing school, instead of Princeton or Stanford.
Whenever I do school presentations, these pants are the one thing that every kid wants to touch and it's very funny when I have the teacher put them on in front of the class.