Hi.
I wouldn't call it a serious boundary issue in the skeme of things but I personally wouldn't accept the request. I had a therapist I was working with for a few years who ended up having very bad boundaries, self disclosed wildly I really think got emotional needs met through her clients. Anyway I was on her FB for awhile and it just got me more wound up that she'd post stuff about her dog dying and relationship issues things like that knowing her clients were on there. She had no filter as far as I could see for what was appropriate to discuss with her clients and what not. Don't get me started on the newsletter she would write monthly often using stories from her own and her son's life as the basis for articles, hence talking about her mother with althismers, her son being bullied, past trauma issues of hers ETC.
So obveously hopefully your therapist is not like that. But I would be careful.