Received Administrative Processing (221g) without any explanation

[Mirou_hml 0]

Hello, I am from Algeria, my visa interview for an F1 visa was on the 2nd of January, the interview went better than my last one (I got refused last time) I dunno what the Visa Officer saw but suddenly at the end of the interview he asked to see my acceptance letter to the university, it was totally out of place I mean he could've asked earlier since he asked all kinds of questions before it , I could see the look in his face changing before he asked that, luckily I had it with me so I gave it to him, he took his time reading it then he gave me a paper that says I was rejected under 221g and he kept the passport, he told me nothing after just that he will keep in mind my date of entry which is on the 31st of January, I keep checking my status and it hasn't been updated since the day of the interview, I just wanted to share this here I know I still have more time to wait, so if anyone got any comment for this feel free to comment ^^