Is this a sign of a bad alternator?
 

Hi yall!
Yesterday while driving I noticed something strange. My headlights and dash lights all dimmed for about a 1 second and came back to full strength. This happens about once every 30mins of idle or driving. The voltage reading on my audio deck reads a healthly 13.8 to 14.4v but I went for a diagnostic anyways at Advance Auto Parts.

Battery is good.
835 CCA
840 Rated
12.56v

Starter Test. Low cranking Amps.
Voltage - 11.13v
Amps - 0.0A (This may have been a bad reading)
Time: 937ms

Charging System Results. No Problems.
No Load - 14.45v
Load - 14.48v (High Beams and Blower(A/C)
Ripple - 17mV (See attachment for graphical readout)

I was told everything looked ok except my Ripple Graph which is basic a straight line. I was told it is time for a new alternator. Is this true?