Demonoid369

So I've been pondering on this and not entirely sure what it is.
Awhile back I noted that when I disconnected my battery(to do spark plugs, wires, etc...) it took a bit to get my fuel gauge to move, well it's gotten a bit worse now to the point that if I disconnect the battery for what ever reason then reconnect it, my fuel gauge chime will go off because the gauge moves so slow that its registering that I'm low on gas(even so I have a full tank) after maybe a min the gauge will finally make it to the correct level and all is good then.
I'm just curious as to why its gotten slower? Can't be the fuel pump since that doesn't have the ballast/thing. Would it be a relay?