Last year, when I was reading up on language acquisition, I read that this phenomenon of children's language acquisition follows a U-shaped curve: First, children learn a few words and phrases wholesale so might correctly say something like 'I went to the shops' or 'I ate my dinner'. But then they start acquiring rules (e.g. that one adds -ed to a verb to create a past tense, as in 'jump - I jumped'). So then they apply this rule too widely, treating irregular words as if they are regular ('overregularising'), so might say the familiar child forms of 'I goed to the shops' and 'I eated my dinner'. And then they come out at the other end of the curve by working out that some verbs don't follow the rule they have acquired and learning how they function.
So apart from making us chuckle, Bee's могол is encouraging: perhaps he is beginning to internalise the grammatical rules of Russian rather than simply repeating phrases. It will be interesting to see if these overregularisations increase as we progress to the bottom of the U.