height violation while extending

[Dave Flowerday]

R08: Once a match begins, robots may extend horizontally beyond the 28-inch x 38-inch starting size under their own power, up to a limit of 60 inches in either horizontal cardinal dimension. The robot may not exceed the 60-inch height restriction at any time during the match. In other words, after the start of the match the robot may expand up to a maximum volume of 60 inches by 60 inches by 60 inches. The one exception to the height restriction is provided in Rule <R13>. Any restraints (elastic bands, springs, etc.) that are used to maintain starting size must remain attached to the robot for the duration of the match.

(emphasis mine)

At no point may your robot be taller than 60". If you have a mechanism that causes your robot to be taller than that temporarily while you expand, then I think it's pretty clear that it would violate R08.