Loud banging noise from manual trans

Hi I bought a manual '03 2.4L 4 cycl 8 months ago and about 6 months ago had the transmission rebuilt.

I've had the rebuilt trans for like 4 months now and I've had this happened probably 6 times, but twice in the last two weeks. Early in the morning, seems to happen more when cold out, I'll be just leaving home in the morning, and shifting into first, and there will be a huge "BANG" noise from my transmission. It almost sounds like a gun-shot it's so loud. One time, there were people on the sidewalk, and this woman almost jumped she was so scared, and her husband like grabbed her. So it's loud.

I freak out and think my trans is gone, but nothing is ever broken, and I just go on driving. Literally no issues at all. I'm going to take it back to the trans shop b/c I have a warranty but wasn't sure if anyone had any thoughts first.

Thanks

 

As you release the clutch or while you're moving the shifter into 1st?

 

It's at the end of the push clutch + shift into first, and feels like I've already got my foot on the gas. So forsure towards the end of shifting, thanks