Dave,
I think that what you were referring to are not upper traps, but the vine pitchers, which appear as clusters of traps along the vine, above the ground carpet.
It's really hard to get amps to do that, and it may be a function of age. A friend of ours has some pretty big amps that are grown in a grow chamber-here in Florida, and they are producing the pitcher clusters along vines that are about four to five feet tall. At this point the vine becomes woody, and the clusters break thru at the nodes.
Also, I suspect you need consistent very high humidity for a very long time to get them to perform this way.
We anxiously await the day ours will do the same!