Wow. A polygamist mother of 3 children who has survived cancer declares (S2E2) that her first day back at college/the U was "the best day of my life" and she's supposed to be taken seriously? SERIOUSLY? Wow. Just wow.
Love isn't what you say or how you feel, it's what you do. (The Last Kiss)
I don't see a problem with that comment. She didn't sit down with a notebook and reflect on her entire life. She experienced something new and different and she expressed that sentiment in a normal way, off the cuff, in the first flush of excitement.
Don't you exaggerate sometimes a bit, or at least realize that others do? It is human nature.
A quick example:
Leaving a theater, you or someone you know might exclaim, "That was the COOLEST movie I've ever seen" but later on, if you sat down and thought about it, you may not think that after all.
You're putting way more weight into her words than her comment warrants. She is EXCITED! and she expresses that excitement in a completely normal and understandable and HUMAN way.