Limit on avg. centipawn loss?

Played 2 short games today with 11 centipawn losses:




Inaccuracy in one, not the other. What am I missing?
Proper opening theory? ...or are there examples where
it gets under 11? Pardon my stupidity...I just learned
about these centipawns. Do the games have to be shorter
yet, or the opponents never "up" at all?

Do not attach too much importance to AcPL.
In the 2nd game Stockfish considers your 2...f5 as an inaccuracy and counts it towards your AcPL. You can disregard this. For example also 1 e4 g6 is counted as an inaccuracy.
Of course it can get under 11, e.g. 1 f3 e5 2 g4 Qh4# is 0 AcPL for black. So indeed in a short game and/or a game where your opponent plays badly and thus gives you no opportunity to play other than strong moves the AcPL can be zero.
Also long, uneventful games can attain low AcPL, e.g. 5 for both players in this game

I recently played a 50-plus move game at a rating of around 1800, and still got 7 acpl. I'm sure I've managed 7 acpl before. Just an uneventful drawish game, start to end.