dash lights pulse:alt problem?

i noticed last night that my dash lights were doing like a pulse action,along with the sound of the fuel pump and everything else that is lit up and it does it kind of fast.i just had the alt rebuilt last year at a local shop.

an alt problem is the only thing i can think of,any suggestions?

oh and the power steering banjo fitting does not leak on the alt either.

If you got an amp for some subs it could be gettin a bad ground... thats all i can think off.