The text you gave an example of doesn't ring any alarm bells. However, the later behaviour you describe says you should run.
For what it's worth, I'm so with Backup when it comes to complainers. Look, everyone is allowed a bad day and I'll listen.....but if the complaining is frequent, then those people just drag me down. There's this person who thinks she's a friend of mine. However, I swear this woman could complain about a sunny day. No matter how I try to drive the conversation into positive or neutral territory, she always finds something to whinge about. (I'd cut her out of my life completely, but she's a school mum and I can't completely avoid her).
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.