Piss on that. Sometimes you need to strike at the biggest moment and the most immediate opportunity. And given that she's been on TV for about a year now, and has spent most of that time either behind Nikki or Charlotte as the one the fans have wanted to have the belt, this seemed like as good a time as any to actually give her the belt.
Actual age doesn't matter. TV age does. There's no point to letting this year old story keep going to the point where people might actually get sick of it (which always happens when you wait too long), especially when you're debuting a new belt. They really should have just had her win the belt here, especially given that she was one of the three most over people at this WrestleMania.