If the timestamps are correct in each case, it looks like it's still less than five minutes since you created the files, which means the ctime test would trigger for that reason. Notably the timestamp on file1 does not change when you edit it, indicating that happened within the same minute of its creation (or last edit.)
Your syntax otherwise seems correct. Here's a simple example from my system (RHEL 7.4), with timestamps to clarify:
[testuser@dc0sandbox01 ~]$ date
Thu Sep 28 10:36:53 CEST 2017
[testuser@dc0sandbox01 ~]$ touch file1
[testuser@dc0sandbox01 ~]$ touch file2
[testuser@dc0sandbox01 ~]$ find . -cmin -1
.
./file1
./file2
[testuser@dc0sandbox01 ~]$ date
Thu Sep 28 10:37:09 CEST 2017
(wait for a minute)
[testuser@dc0sandbox01 ~]$ date
Thu Sep 28 10:38:11 CEST 2017
[testuser@dc0sandbox01 ~]$ find . -cmin -1
[testuser@dc0sandbox01 ~]$ chmod 660 file1
[testuser@dc0sandbox01 ~]$ find . -cmin -1
./file1
[testuser@dc0sandbox01 ~]$ date
Thu Sep 28 10:38:26 CEST 2017
If you still have problems, try using the stat command to show detailed information about each file:
[testuser@dc0sandbox01 ~]$ stat file1
File: ‘file1’
Size: 0 Blocks: 0 IO Block: 4096 regular empty file
Device: fd02h/64770d Inode: 286973 Links: 1
Access: (0660/-rw-rw----) Uid: (10131/testuser) Gid: (10131/testuser)
Context: unconfined_u:object_r:user_home_t:s0
Access: 2017-09-28 10:36:56.331274189 +0200
Modify: 2017-09-28 10:36:56.331274189 +0200
Change: 2017-09-28 10:38:21.872727064 +0200
Birth: -