May be the same issue as with Cloak of Shadows that Fleurs reported, but I ran into this (abbreviated):

Magic Item Use.....................| 220 120

J>rub my pin
J>
You rub your citrine quartz pin.
Feels smooth!
1d100: 69 + Modifiers: 84 == 153

J>prep 215
You gesture.
A brilliant aura surrounds you and sinks into your skin. You feel charged with extra vitality.
Cast Roundtime 3 Seconds.


J>spell active
You currently have the following active spells:
Heroism ............................ 0:19:10


Looks like I only got the base 20 Minutes, instead of the (I believe) (1200 / 2) + (120 * 1 * (60 / 2) = 600 + 3600 = 4200 Seconds = 70 Minutes


Is my math off or is the duration short?