Thank you for your reply.
I noticed it does not do that with other docs files I have, but only with the TAGS sheets, and I also changed the password in Google just to stay on the safe side.
I checked the permissions on the files and they are all set on private (I had not touch anything before anyway). The only change I made was on the trigger, to increase the time between triggers (1 to 6 specifically).
Any other idea?