I purchased mine at NM, so it is authentic, but do you ever have the problem of accidentally popping off the clasp that holds the pocket shut? I *love* this bag, but this feature irritates me. I've only had it for a month, so is mine defective, do I need to take it in? It pops open sometimes if my hand knocks it; sometimes randomly. I'm just wondering if I am the only person with this problem. Help!