I'm like that too, except I don't have the "flurry of new messages" excuse. More often, if I let it go when I first see it, it slips out of my mind. It's like "Well, it wasn't important enough to respond to the first time, what's different now that makes it important enough to respond to?" (regardless of whether it actually is important enough to respond to).
It's not that I'm mulling them over, it's that they get overridden by a new flurry of messages. It's hard to keep up.