This one's pretty weird. I'm guessing that the vast majority of pump users don't experience this, because my (completely speculative) theory is this is a result of the quantity of insulin infused (due to insulin resistance).
I have a location on the back of both arms that has been hit many times as an infusion site with my pods. I try to keep moving the site around, but I got lazy, and went for 4-5 months on the backs of my arms exclusively.
Now, when I administer insulin with the pod somewhere else (currently on the left "love handle"), I get a little sting on a spot on each arm where I had infused insulin over and over.
Not always. But probably 1/2 the time I feel it. I get it when the pod is on one arm -- feel it on the other.
Keep in mind that my I:C is 1:4 -- so when I have 40g carb for lunch (a sandwich), I'm dumping 10U of humalog to cover it. That's a lot.
Anyone else experience this? I'm guessing it'll go away with time. Doesn't really bother me... just kinda interesting. Akin to "phantom limb" syndrome in a sense :-)