Yes, for sure. While we're still mourning, it does bring me some peace knowing it wasn't some dumb rookie mistake I made.
Sadly, there was no way for the doctor to tell how long he had it or where he could have definitively gotten it from. He guesses it was for a while because of how pronounced it was, and because it can take a long time to build. We had Bonzai for 2.5 months and he said he could have had the beginnings of it before he even got to us. He could have gotten it from feeders, or from another reptile. But it's all just a guess.
During the time we had him, we gave him f/t pinkies from two different sources. One was from PetSmart, and the other was a local mom & pop pet store. From the little pet shop - I can't remember the brand name of the pinks, but they came by the dozen in a little blue box, individually sealed in plastic. That was the brand of the regurged mouse. I'll get the name when I get home, I think I still have some in the freezer.
The two live feeders also came from two different sources. One from a local specialty reptile store and the last from a BRB breeder in town who also sells his own mice. But Bonzai was already sick by the time he got those, so I don't think it was the live feeders.