It could be for a number of reasons. I happen to know that in this case it was because of one anomaly in the subjects.
Though, an increase in a free hormone whether due to changes in binding globulins or other reasons isn't unusual.
Carbolin 19 is forskolin with two ethylcarbonate esters. Again, once those esters are cleaved, you're left with pure forskolin. Thus it's expected that the same effects will be achieved, if not better due to better oral bioavailability.
Hope that helps.