No, probably because at a certain zoom level, the TAC would not fill the screen. I guess iFly would not know you are just temporarily looking at the sectional and plan to return to the TAC and current zoom level.
EDIT: Well I was just looking at the CLT TAC and dragged it off to the side to see something "off the chart." It showed the sectional for that area, but was still on TAC when I dragged it back. So, instead of zooming, try dragging the chart. Then, tap the bullseye to recenter on your aircraft.