Can Tech Dept/GM please answer this question.

The other day a coupon refund issue was resolved and my coupons refunded.This happened at the exact time i was playing crossfire(i know this because 20 minutes before i had checked to see if i had a reply to coupon issue).
The point that got me paranoid was that ingame i got a message that i was disconnected due to somebody sharing my id.
Upon receiving this message i immediately changed my password at the homepage and then i noticed that the coupon issue had been resolved after seeing message in my inbox.

So the question i would like to ask is:When the Tech support team resolved the coupon refund issue did they have to log onto my account to do this causing me to get disconnected while changes where made(70 coupons refunded and the AWM camo withdrawn from my storage) or was it just a coincidence and i should be concerned that my account appears to be compromised.

I must add that i am a mature player who has honourable ribbon have never visiting any hack sites and have never given any of my personal details to anybody.

So i am bit concerned at what happened.

I would greatly appreciate some feedback from somebody who knows about coupon refunding if in order to make changes they must access my account or has my account been hacked/compromised?
If it has been compromised apart from changing password is there anything else i can do to increase my ID security?