Looked those up specficially and they seemed to be flagged properly. I won't be able to do some testing for a while today but if you want to be 100% sure then make a copy of your save(if you don't want cheater flags) and then follow this here http://www.gamefront.com/torchlight-2-dev-console-commands/ . Turn on god mode and let yourself get pummeled for a bit and see if any crits pop up.

A bit hard to pin down which was the cause as it happened fast, could've been a Hulking Slasher or Mirka Frostbinder.

I didn't see anything. It would help a lot if you could provide me the specific name of the monster that crit you. Thanks!

I'll give it another pass, there's a good chance that I missed one.

Are you sure you got all of the monsters? The frost casters in last half of Act 1 may still crit, as I just died instantly to them, much like I got crit. It may be their base damage is just that high, though.