I'm 99% sure that this means that I need new calipers... both fronts on my Tundra have some sort of damage to these pistons. Or at the very least a rebuild. From what I can tell, the pistons are amazingly still free though, so I'm tempted to buy a rebuild kit. However I've never worked on a 4 piston caliper--do you just open the bleeder and push down on the piston, and just that piston will move? It's been a couple of years since I messed with those bleeders, and I didn't think to see if they were loose yesterday. Alternatively, is there a downside to leaving it alone? I'm guessing if it seizes, it'll just be like a single piston caliper, and cause a dragging brake when it goes.