Guessing it's probably about what Watame mentioned yesterday, about how Flare had told her how she really likes Watame's original song 'My Song' and it made Watame tear up a bit to hear that. I'm guessing that's it...although knowing how empathetic Watame is I'd also guess she must have been pretty happy about her friend passing 1mill subs...but yea, she specifically mentioned the song thing yesterday, so I'm going with that.
Yep, probably is that, Watame tweeted about Flare almost crying while singing "My Song" and said she cried too, and to keep doing their best, if I'm not mistaking it the tweet was something like that xd