New owner here. Is this normal behavior?

[Crowfingers]

10g difference? Then you are not buying rat pups.
Rodent pro lists at 20-29.99g
Big Cheese lists at 20-34g

This is why I post the same chart as posted above.
There is a weight range per size.

Sorry, that was a mis-quote, just checked my bookmarks; I have been looking at rodent pro fuzzies vs big cheese pups the whole time sorry about the confusion. I bought pups, and weigh each one at feeding time, they are between 22g and 29g.