Disconnecting the battery cleared the PCM's KAM. When it is reconnected the computer has to relearn all it's parameters. It is rare but when first reconnected, the car may stall as the PCM relearns the idle speed parameter. If it doesn't happen again, your ok. IF it does well then you can start looking at maybe IAC valve problem or something else for that matter.
When your IAC valve goes bad (at least when mine did) it begins as a VERY intermittent problem; however, once the engine has reached its operating temperature, the IAC won't cause the engine to die. Again, this is what mine did; I had to give it throttle until it warmed up, then it ran fine. If I stopped for a few minutes and restarted, it started up without a hitch.