Because Virgie Rachley FBI statement refers to Carolyn Arnold, as having"accompanied" Rachley going outside of TSBD at time of 12:15, and yet Rachley did NOT see Oswald, then the sighting of Oswald IN the 2nd floor lunchroom by Arnold, in isolation, is a curious detail.
The door of the lunchroom would have to be OPEN to see anyone sitting at a table, if just bypassing thru the vestibule, on the way to the short 30 ft outer hallway, and then to a water fountain.
Reason given by Carolyn Arnold, in the Earl Gotz 1978 newpaper article, to go the 2nd floor lunchroom was "to get some water".
It is unclear is there was actually a sink with faucet IN the 2nd floor lunchroom or not, however.
There IS for certain, a water fountain located in the 30 ft section of outer hallway, between mens and womens bathrooms.
So its a question if Carolyn Arnold may have gone out the office back door to go to the water fountain, and then went down the 50 ft length of hallway , and then joined Rachley exiting the front door, which would be 12:15 approximately. There after "accompanying" Virgie the rest of the way out of TSBD.
If its the water fountain, then either Oswald was seen because Oswald was coming out of the 2nd floor lunchroom door, thus opening it, AS Carolyn went thru the vestibule, OR, when Carolyn was at the water fountain,, "getting some water", Oswald opened the HALLWAY door!!
If Oswald was opening the hallway door, that could only be to ENTER the outer hallway. And if Oswald was entering the hallway, it was probably for reason of going down it himself, to then head towards the front staircase, because HE TOO was taking the easiest route to get "out front" to "see the Presidential parade"