I changed the rear pads and rotors last week and I noticed a small tear in the rubber boot covering the piston. Is this tear big enough to cause problems down the road?

<a href="http://s55.photobucket.com/albums/g127/pdkwon/?action=view&current=IMG_0985r.jpg" target="_blank"><img src="http://i55.photobucket.com/albums/g127/pdkwon/IMG_0985r.jpg" border="0" alt="rear brake boot"></a>

Clean it up with some brake cleaner or rubbing alcohol. Just dab the spot with a bit of black silicone, weatherstrip adhesive or something similar, working it into the cut a bit too. The theoretical issue is whether dust or water gets in there and screws up the piston over time. I've had much worse cuts or cracks than that on old cars that I have let go for a while.

Next time you do the brakes, change just the seal--You can buy the rebuild kit from the dealer for about $25, which includes both the outer seal and the piston seal. Maybe others sell it too. If no issues with the caliper, just change outer seal. Simple screwdriver work to pry old one off and new one is fit by hand with just thumb pressure.