I'm guessing you're right, and another possibility is that the presence of other baby niles may have kept them reassured that they were in a safe area. Similar to how hunters put out decoy ducks to draw in the real ones.I think that their competition with each other for food, territory, & so on made them focus more on each other than on me; there isn't really anything else to focus on now that it's just the one in there.
I highly doubt that it was given very good care by the vendor that I got it from, but I doubt that would have a major effect a little over four months later.
I forget what I said their original lengths were, but I believe this one was in the 10-12" range when I got it, so it's been growing at a rate of around 1.5-2" a month when it should be growing at a rate of 2-3" a month; if it had grown at the optimal rate, then it would've been in the 18-24" range by now. My goal is to have it to a size that will allow me to determine the gender before the end of the year, so it needs to cooperate & hit a big growth spurt!
I was of the same opinion, usually sellers don't care for them exceptionally well. It depends on how long it was in the seller's care, if they had it for a very long time, it may have gotten past the age of the initial explosion of growth, and is at the age that it puts on growth spurts instead.
You've had them what, five months? That's not too bad as far as growth goes, not sure I'd call him a runt.. He may not be a really big guy, but I think he'll still get plenty big.

