I don't think he did realise. Long ago, his default response to any problem was to run from it - I think he was more focused on the running, and the getting away, not thinking about the actual "threat" he was running from. Where he came from... he had a lot of reason to run.

It's only recently he's learned to stand his ground, especially when it really counts.

Something's bugging him, and it's bad enough to make him take a big step backwards. But... it only started after you all were fighting, back when Marco did that thing...