Scenario:
Finish Candlestick Keep (near the end of stratum 4) with one and a half pips of life left, and two dead teammates.
Heart comes up on the wheel. Move down to the next level.
Result:
All of us are revived have three hearts. This is normal. However, I don't have the bonus hearts awarded from the wheel.
On a related note, I never get the text saying what I won if there is meant to be some.
As a rule, the prizes are awarded on the spot... So it depends on what size heart was it? A large heart (2pip) should had put you up to 3.5 total, but a small heart would had put you at 2.5.