So, I decided to play around and find out what was causing it and how to fix it.
What I found was this:
So far, it seems that the cause is holding the toggle view button during a kill animation (R3 on the ps3). I was able to fix the 3rd --> 1st person switching by doing exactly what I think was causing the issue in the first place: find a bandit or someone with low health (where you are pretty much garaunteed a kill animation), HOLD the R3 button, THEN attack for the kill animation. This fixed the issue for me (at least for now).
Hopefully this helps. It might be useful for toggling between kill animations, if you desire one or the other type.
Disclaimer: this worked on the ps3, so I'm not sure of the viability for other platforms.