frost / swamp potions
 

I can't remember which one of those made me raise my alchemy skill to 171 before coming trivial.

According to that link, they both should be trivial at 170.
http://www.scribd.com/doc/6936249/Th...e-Trade-Skills

If it was intended to be trivial at 171 skill, then there is no bug, else one of the two potions if not both need to have their trivial level decreased by one point.

curious about this also, tried using the trusty search function but came up with nothing. at first i just thought i had horrible luck when i failed 3/5 potion of the frost combines, but then double checked and noticed I wasn't getting the trivial message while @ 170 skill.

well, failing 3/5 potions at 170 skill is still horrible luck :)