I had this done at 38 weeks, it didn't work for me and they did it twice.
My sister had her membranes strip but she was 39 weeks pregnant. Its to help move thing along. she went in to labor 2 or 3 days later.
Hi, I would recommend asking her directly to explain what the reason for the procedure was and maybe also ask her why she didn't actually explain it all to you beforehand. Please let us know how you go. I've never heard of this being done - sorry I couldn't be any more help. Good luck and best wishes for you and bubby.