Guys - the original post misquoted the message, which apparently read in full - "I am sick. Thank you for you patience."
Based upon that and not even knowing who the Agent was I'm not prepared to comment beyond saying that I find nothing strange about it at all and if I had received it I would wait a month or so then follow it up with an expression that I did hope she was feeling better and able to get onto tackling what I hoped wasn't too daunting a backlog.
The message was brief and concise and to the point - maybe even sent by an underling.
If this is true that is entirely different, and I'm a bit curious as to why the OP edited the reply so heavily if she (presumably) wanted thoughts on the unedited reply she had received....