VegasKathy,
I don't know what the minimum is that you have to gamble but you could always call the Trop and ask them what you were rated during that trip to the Trop. They rate you 1 - 9. The lower the rating, the better and they average your last 6 trips.
In the case of my Wife and I, we gambled a lot. Me playing blackjack at the green chip tables and the Wife playing max coins ($1.25) per spin at video poker. We each have been averaging over 8 hours a day gambling at the Trop. Also, when playing the machines (slots or video poker), the number of hours is tracked but also the average $ through the machine per minute. So it does matter how fast you're playing. In other words, playing the machines, it's more a matter of how much $ you're putting through the machine per minute than the total time you're sitting there and occasionally pulling the handle.
I'm not implying you weren't playing as many hours as you think you did, only that they look at the average $ put through the machines along with your total time you play at the machines.
And at the Trop, you could always check those numbers at the promotions desk during your stay to see how you're doing. For example, if you play quarter slots, they will track two numbers: total minutes played and a second $ amount. This $ amount is the average $ put through the machine per minute. From those numbers, you can calculate on average how many spins you made per hour (assuming you played the same $ amount per spin).