SSS and gear binding

So I just bought some blm crafted i380 gear to see if my dps would improve on the sss dummy. I failed the first attempt. However on my second attempt I cleared it and then the gear I bought was bound to me even though I never hit an actual enemy. Is this a glitch or is it working as intended?

Gear will bind when you do anything with them other than just wearing. I had some glamour stuff I made a couple years ago bind not long ago after someone in the party I was in got into a fight in the area I was in.