After enabling the hardware IWDG, I noticed that on subsequent SW programmings, I always get an immediate single IWDG reset event. After that reset, the system boots, but it seems to boot several times faster than what I remember (I need to measure the timing). Also, the timing from programming to IWDG reset looks to correlate with what I have in the IWDG_RLR. The interesting thing is that I don't see this if I perform a power cycle, manually press the NRST button, or when I enter into debug mode.
Any ideas on what is happening here? What could be different about a reset after programming the mcu vs a power cycle? The MCU seems to be booting with a different clock selected by default now.