Scuba's correct. When it comes to why a balloon pops, it could be anyone of a number of issues, many of which there is no definitive way to state what was the cause.
It could be a weakness/non-visible defect in the latex. It could be something like static, or a something in the air, that caused a reaction that popped it. Temperature coudl be a factor. Something on your clothing, your body, or your skin may have reacted.
It could be a combination of weight, pressure, tension that just caused it to stretch too far in one way, or twist or contort in a way that the balloon couldn't handle, so it ruptured.
Sadly, unless you can find an obvious reason (e.g. a sharp object, an obvious defect in the balloon itself), then you will just have to accept that balloons can, may and will pop at any time and for any potential reason, and it's the one issue we only have a small amount of control over.

It's annoying when it happens, but if you felt that the balloon was defective, and shouldn't have popped, you could always contact the manufacturer, send them an e-mail, and see what they say. Some will send out replacements. Some may ask to send the balloon remnants back for tests/study. Some will just say "tough luck". But for a GL, you could try sending an e-mail, and hoping that they come back with a positive response. It's really a case of do you believe it's worthy of your time to do that, or just better to forget it and move on?