Ok, I just played through the game myself and compiled screenshots of all the levels, would you be able to point out what you mean in whichever level is applicable? I cannot see an area that contains these free passages you've specified.
Screenshots
I died a couple times almost immediately without previous hits. I think maybe it collided with enemy several times somehow and received multiple damaged.Hmm, that shouldn't be happening, I'll have to look closer at how the damage works (I never came across this happening in testing)
I will add, you do keep any damage you take between levels, if you die immediately in one level you might have been hurt in the former?
Nevertheless I'll take a closer look to see if I can replicate (/ find someone who can replicate) the issue and find a fix.
Thanks again for all of your help :)