1995 Honda civic.speedometer drooped and radio turned off for a second while driving. why would this happen?

I was driving on the freeway and the speedometer and my stereo shut off a second and came back on....the car didnt shut off...as I got off the freeway it did it again so I pulled into the nearest Kragen where they checked the battery and alternator, which checked out fine. They told me it might be a relay? If anyone has any idea of what might be causing this it word be greatly appreciated.