For everything else it takes super long to get it started, but for the healing centers it's just "okay, you accidentally bumped the A button, so now we're going to go on a rant about how good we are at taking a long time to heal your pokemon!!!"
So true. I always just pressed B. In fact, I have pressed the B button so many times, that it's like loose or something on my DS. It makes me worried that maybe one day it won't come back up when i press it