Delete this please.
That's the standard amount of XP that you get from pet masters, and Squirt is no different in that regard.
What makes her so special, is (i) you can battle her over and over, rather than once per day like most masters; and (ii) she's standing right next to an NPC with free healing for your team. Great when you want to do some grinding.
She was particularly effective/lucrative earlier this month when her visit was aligned with the bonus event, as Mymori stated above. Could level a pet from 1 to 25 in two fights, roughly six minutes of effort.