I know any battery can leak, and you need to be proactive and replace them. But I've had terrible luck with Costco's Kirkland AA batteries. They have leaked in several clocks, my kid's toys, and they almost ruined a wireless transmitter for a weather station. In the last month I've probably come across four that have leaked. I've had other batteries leak, but never this many and this consistently. Some Google searching shows that I'm not the only one having problems with them. I'm taking them out of all my pins tomorrow. I'm also going to contact anyone I've sold a pin to and have them check if I put these batteries in them, and tell them to replace them if they have them. If you have any of them in your pins, get rid of them.
Edit: The ones that leaked in the wireless transmitter are dated March 2014.