I don't know.
I'm an expert on T45 problems, which there are several. But many of them were fixed, or at least made considerably better, when Tremec took over production from Borg Warner (for 99 and later cars) which had some serious production (for 96-98s) problems. But usually its grinding, not a "jumping in" problem.
2300 is fine for daily shifting. Actually I'm not sure what to tell you. I have heard of clutches being a bit "grabby" in certain gears. Maybe your clutch is "grabby" in second? /shrugs/
Even with the T45 issues, in my experience Mustangs are by far the easiest manual I've driven.
My only question: Does it vary from when the car is cold, to when the car is warmed up?