Don't close the app before you finish all your "first 20" swipes of the day (the ones that get you the bowling-a-spare points that Chelle so succinctly explained).
Today I got a few Monopoly ads first and those credited as expected at 30 silver. Then I wasn't getting any ads at all so I closed the app. After I opened the app after a while, I got a Monopoly ad again, but instead of 30, it only credited at 15. I still didn't catch on, and when there were no ads after several swipes, I closed the app again. After I opened it, another Monopoly ad, but this one too only gave me 15. This time, I wised up and left the app open, came back after a while, and the next Monopoly ad gave me the correct 30 silver.
[CellNuvo veterans here probably already know this, but newbie me noticed it only today so thought I'd pass it on].
I suspected that might be true, but hadn't confirmed it. If I plan on closing the app during the 'first 20', I do so after a 1-2 silver ad (even if that ad has a 15-silver 'bonus' stacked on it.) That way, you're only losing a 1-silver bonus.
The CN app crashed on me while attempting the swipe following a 15-silver ad, and I was upset that I was going to lose that 15 silver bonus on the next ad. After restarting, I still got the bonus on the next ad. So it appears that closing the app may break the string, but crashing the app may not.