Not everybody has a calendar in their heads(myself being one of them), and as Toys R Us is one of those places that is strict about return policies, I am sure the cashier wasn't going to risk getting written up over your return if it had been more than 90 days.
And, nobody cares how much money you spent in the store. You deserve no better or worse treatment than me, who spent about $150 in there this Xmas season.