It's distinctly possible she is being polite with you if she didn't express disapproval or discomfort (although you should stop telling everyone about these matters regardless).
But dude, paying off student loans for work acquaintances is well outside the boundaries of socially normal behaviour. People don't do that, and if she's remotely normal she'll be more scared and horrified about what such an acrion indicates about your perception of your relationship with her than grateful about the debt being gone. Plus you could get in trouble at work and compromise your job for creeping out coworkers with socially abnornal behaviour. Don't do it.
If you actually like her and think there may be any mutual interest, ask her out. If she says yes, you can consider offering to pay off her loans further down the line if that goes anywhere. If she says no, you can be certain this is a bad idea to entertain. At any rate, don't get too ahead of yourself.
