funny you should mention this, thunder. i came across the exact same situation earlier this week, and had the same, "aha" moment in regards to tilt.
i emailed my brother about my discovery; i just didnt feel it important enough to post here. why? i have no clue.
i went up about 1.5 BI's in some cash games over about 800 hands, and proceeded to take a couple smallish beats and then donk off the rest (about a BI) from stupid shit...3barrelling call stations, etc.
i stopped and realized what i had done, like you i didnt give a rat's ass while it was happening, and concluded i was tired. i had played a lot, for me, and was simply worn out/bored with poker for the day.
i learned about 1000 hands is my limit. i hope you learned something about yourself, too.