This has been a "quality of life" issue for me for a while now- command-line editing in the Mac terminal is messed up for me.
If I type a few chars, and then hit CTRL-A to move to the beginning of the line, it'll move the cursor too far over. It seems like what's on the screen is out of sync with what bash really has in its "buffer".
For example, I start typing "ls -l":
... and then hit CTRL-A to move the cursor, and I end up with the following on the screen:
I think the following snippets from my .bashrc are relevant to a potential diagnosis:
export PS1="\[\h:\w\]\$ "
export SUDO_PS1="\[\h:\w\]\\$ "
set -o emacs
FWIW, this also happens to me while using iTerm2 instead of the Mac default terminal.