Part of the reason I've been getting the older models--P4, E4 (EL), and S4. The quality is a lot better on them as well. It did that on my PS4 after storing it for two months and opening up the scissors. Eventually, I'm turning it in on the voucher program and putting the funds towards a full-size tool (or some sheaths and the bit kit). The issue is well-documented, and common, so why hasn't LM fixed it yet?
More interesting to me would be what causes it--metal fatigue due to the position it is in when closed, over-hardening, or both? Maybe if they used a separate, replaceable spring like Vic, this wouldn't happen.