It get's old when every dog you see is the cutest ever, every movie is the best ever, every thing you eat is the tastiest ever.
People really do overuse hyperbole
If you're frequently over-the-moon with joy at your meals, your movies, the animals you run across, your job, or whatever, it seems like a fundamentally good state to be in.
I also have friends who do this, where it seems to be a mask they put on. These friends often have rather unpleasant pasts.
It's a bit like the manic pixie dream girl, to use a fascinating stereotype. I have often tried to delve deep, and it's sometimes really hard to discern the 'broken' kind from the truly 'child-like' type.
Broad strokes, I know, and please forgive me. The only point I want to make is that context is everything in this case.