You need to be careful with sampling oscilloscopes. When you slow down the timebase you can miss events if you select the wrong mode. I don't know specifically the options available on the Agilent oscilloscopes but you need to read the manual carefully to choose the best mode. I almost always run my oscilloscope on 'envelope' mode. That runs the sampling as fast as possible and displays the maximum & minimum values on the screen so glitches aren't missed. That may be called peak detect on the Agilent.
If you slow down the timebase and have, say, 500k points to display, the oscilloscope has to reduce the number of points to fit on the screen. The simplest method, possibly called 'normal' is only to display a limited number of points and discard the rest. That gives a high chance of missing glitches.
Keith