So here's my specific reaction now:
IF she posted - "hey, I'm a literal angel!" - very odd and would have me wondering about the poster's mental condition
IF "hey, my friend Mary thinks I'm an angel/sweetheart" - I would think the poster was bragging ridiculously and would think it very odd
IF "I just wanted to share this poem with you because it made me think of you: - I would personally think it a bit saccharine but sweet
Unfortunately, I doubt we'll ever know what it actually was although I think the third and second options, respectively, are most likely.