Update: I know I started this thread and then disappeared, but that's what has happened for the last 6-8 months. Either muscle memory is pushing the pedal harder and I'm not noticing or the problem just went away. I know that doesn't help give a definitive answer. But its been fine for a while. I even installed the USP clutch line and its still starting fine.

Now I just had an idea, maybe that delay valve that the USP line bypasses could help remedy this issue?