Did this part come out of my Mac Mini?

I installed a new SSD into my Late 2012 Mac Mini last week using instructions from this site. Getting the logic board out was difficult, and when it finally came loose it do so very abruptly. I managed to knock a capacitor off the board, which I have since repaired, but I also found this mysterious rubber part on the floor.

I assumed it came from the Mac (grommet? strain relief?), but i couldn't figure out where it went during reassembly. Any ideas? Or did I just find something funky on the floor?

Follow-up: Once I followed Dan's advice and looked on the inside of the back cover (instead of trying to fit it around the power jack and then replace the logic board), it was obvious how this part fit.

Great success! Thanks again!