Speaker 'pop' after relocation.

[AbsentAbe]

I need some help with this. I moved my receiver yesterday from the right side of my entertainment center to the left in order for all of the connectors to reach the back of the receiver and cleaned up in the process. Now I am getting an eventual 'pop' from my speakers. I think it may just be the center speaker, but I am not sure.

I wasn't the one who originally set it up; that was done by my brother, so I don't have much experience with hooking up speakers.

I was wondering if this problem could be from the wiring, connection, the speaker itself, or the receiver. It has been stationary for years so there was dust behind the receiver. Could dust at the end of the connections cause this to happen? Or did I just not connect the wires from the speakers to the receiver properly?

I checked the connections from the speakers to the receiver, and they are snugly in place.

I also vacuumed all around to clean up the dust that has been sitting around, if that may be a possible factor for the popping.
I didn't have any movies playing when the popping happened, so I know it is not any kind of player or disc problem, but it does still happen during movies.

Any advice on what to do to correct this?