Currently invitations can have longer text put into them than shows up in the invitation (or at least than shows up in the invitation if a user looks in their 'sent' box).

It could be good to either remove the limitation (if it's real), or show the full invite message in the sent area. I had a moment of panic thinking that these people who I was already a little nervous asking to join me in SuperBetter were getting truncated invites that would seem incoherent.