Glock 19 standard 15 round magazine question

I've owned my Glock 19 for about a year and a half now. I've put about 750+ rounds through it over that time using the two original magazines that it came with it. I've used the same magazine for home defense and concealed carry since the time I bought it, and kept it fully loaded. I've noticed recently that if I have 8-9 rounds or more in the magazine it makes a rattling noise when I move it around.When it's fully unloaded it does not make the noise, but once I go over that number of rounds it does. Any ideas on what could be causing this? Should I throw this magazine out because it doesn't sound safe to me? Any help would be appreciated! via /r/CCW https://ift.tt/3gsIh27