Whether you're looking at the reverse spectrum of a single amplifier or the entire network, a signal within that 35 MHz bandwidth will take a finite amount of time to go from point A to point B because of the velocity of propagation through the amplifier, the cables and all the other parts that make up the system. Velocity of propagation usually is a bit higher at the center of the passband than it is at the band edges. A signal takes a finite amount of time to pass through a circuit, an amplifier or the entire system. This is known as propagation delay or transit delay, or just plain delay. Signal delay also can be thought of as the slope of a phase vs. frequency curve.
Absolute delay is the delay that occurs at some reference frequency.
Here's where things start to get a little messy. If the phase shift changes uniformly with frequency, no problem. The result is called delay distortion or phase distortion and is expressed in units of time, typically nanoseconds, relative to a reference frequency. Envelope delay distortion expresses the instantaneous slope of the phase shift characteristic and is the difference between the envelope delay at one frequency and the envelope delay at another frequency. Envelope delay distortion often is called group delay distortion.