Roboform asks to save password

I perform authentication with passport.js. However after session is created, after each AJAX request RoboForm asks to save password. Can't figure out what could be the reason.

Here are the headers:

Request Headers

Accept:/
Accept-Encoding:gzip, deflate, sdch, br
Accept-Language:en-US,en;q=0.8
Connection:keep-alive
Cookie:connect.sid=s%3AjvQRBQY...
Host:localhost:3000
If-None-Match:W/"140-3603896551"
Referer:http://localhost:3000/
User-Agent:Mozilla/5.0

Response Headers

Connection:keep-alive
Date:Wed, 26 Apr 2017 11:42:51 GMT
ETag:W/"140-3603896551"
X-Powered-By:Express

via Maxim