I can almost guarantee it was American Express. The same thing happened to me last week. I've always been good about paying and nothing has changed in my income or debt in a long time, yet they still lowered my limit. Not too long ago, they were only too happy to keep raising the limit--until we asked them to stop.
My boss got the same notice the other day from American Express and he also says he hasn't added to his debt and has been great with his payments. This must be happening to a lot of folks.
You can get as technical as you want about the late payments, but I obviously have been attentive of my payments.
I am canceling my account.
Ridiculous.