I believe they are not much older than that. Their appearance looks to be about that growth rate. I think the pet store employee did not know really how old they were, or maybe even counts tadpole age. I would be willing to guess the larger one is a month and half (give or take) and the smaller one seems to truly only be a few weeks out of the water. That's purely just a guess though. I think in a month or so, you will be surprised by their growth.