Thats funny... my G Pro came with a 1.8a LG charger, my G2 came with a 1.2a.
Yeah you'll be fine. The "extra" amperage in the charger is available capacity that your phone can draw from, it will regulate itself but that can also depend on the charger and how they pin the USB. Its different than if you have extra volts (like a 10vdc charger which would provide too high of a voltage and damage electronics). I usually charge all my phones at when I get home with my wife's iPad charger super fast. Likewise you can use your LG charger to charge the iPad but will be slower since it has less amp capacity to supply. Part of the reason they provide the bigger charger is to sustain battery level while using the device (It should be large enough that the battery doesn't drain while your using the device while plugged into the charger).
Most computer USB ports typically provide .5a of power and will be your slowest charging option, at best you get a newer laptop with "high capacity" ports and it provides only 1.0a.
-Cal Naughton, Jr.