The Black Stars suffered a stunning 1-0 loss to the Brave Warriors in the first of two preparatory games for the June 21-July 19 championship in Egypt.
Manfred Starke scored the solitary goal in the 35th minute, with Ghana missing an opportunity to level the score when Mubarak Wakaso stepped up for a penalty in the second half.
"Not actually," Appiah said when asked whether he was surprised by the scoreline, as reported by Ghanasoccernet.
"We went out there to win. The whole of the week we'd loaded them [Ghana team] with hard training so there was some heaviness.
"But the bottom line is to get our final 23 [players for the tournament] so I had to let some other players player to get my final 23.
"Namibia had one chance and scored. Unfortunately we created many chances but failed to score but we are looking at the essence of the game.
"We're looking at the shape of the team so we can see where there are lapses and loopholes that can be corrected before we go to Egypt."
Appiah is expected to unveil his final squad for the Afcon on Monday, four days before the Black Stars take on South Africa in their second friendly.
Ghana will face cup holders Cameroon, Benin and Guinea-Bissau in the group stage of the continental gathering.