I am getting some light popping when i let off the gas around 2K or less

i was on my way to englishtown yesterday (which if you missed it, you really ddint miss much), but on the highway, when im at crusing speed, roughly 2400ish (4.10s=65mph) and let off the gas, it get a few small "pops" coming from the exhaust. I dotn know why this is. I checked my plugs and they are a "rust" color, which, according to the autolite website, is normal with fuel addatives from gas. Timing is at a conservative 12.....

Any ideas?? Is this a bad sound to hear?

Yeah, i know that i have a slight exhaust leak off the X pipe.

is that positively what that is?