Following an account creates a notification.

Some percentage of those account follow notifications turn into profile checks.

Some percentage of those profile checks turn into follows.

People like the other accounts I tagged in that message keep following and unfollowing as a method of free, automated advertising. It's SPAMmy and their content is automated.

It's the first time you've followed/unfollowed me so perhaps it was a fluke on your part, but those other accounts are constantly doing that crap.

If you aren't intentionally doing that, so be it. Everyone deserves second chances. Those other accounts do that crap daily it seems.