Ciphers failing to cast?

[Stereophobia]

I've only noticed this with my cipher, mages and clerics seem to be OK. Quite a few times my Cipher will go through the whole motions of casting a spell, voice, hand waving, spell glow, only to then go back to reloading his crossbow. No spell is cast, and no focus is lost.

 

Is this a bug or something that can just happen with this particular class?

[wanderon]

perhaps he was interrupted? in which case he fails to cast but doesn't lose his spell or focus

[anameforobsidian]

I've noticed it happening, but normally it means the target they were casting at is unavailable now, or they were interrupted.

[Starthief]

I've seen it happen too, and I don't think there was an interruption at the time, and the target's still alive.  It seems to happen more with the longer cast time spells.