Was this inappropriate for my cousin to do to his daughter?

So my cousin is 34 if that matters. He has a daughter who is 18 months old. He and his wife brought her over at Thanksgiving. Very well behaved kid. Well, at one point they were sitting on the floor in the living room playing with her. So she started walking away from my cousin. My cousin jokingly said "come back here!". He took like two fingers and grabbed her pants, while she was walking away. I THINK he very gently tried pulling her his way. She resisted, lost her balance, and fell down, and started crying. I don't know if im being overly sensitive or if this was out of line on my cousins part.

Was this inappropriate for my cousin to do to his daughter?
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