Last night after I got my shot a little bit of T came back out of my leg. My gf said it was less than a drop but I'm just wondering if I should be concerned?

If it's really just a tiny drop or, like your gf said, less than a drop, it should be nothing to worry about.

No, it happens. Sometimes some of it trickles back out.

Leave some air at the top (at plunger) to push the T further into the muscle (makes a raspberry sound when you're done injecting) and leave the needle in for 60 seconds before you yank it out fast. Do it that way and it's extremely unlikely that you'll lose any T.