Is this anything to be concerned about ?

This is a threshold you set yourself in your linodes settings tab.

If this is average disk i/o for your linode then there is nothing to worry about. I believe 1000 is the default but as long as you know why its that high, there is no problem.

You can use iotop to see what is using the most and your charts to see if this is normal activity, if all seems well, just increase the threshold in the settings tab.

I found out the same yesterday.

I was getting these every day in the early morning. turns out I am doing my own tar backups then. It took me a bit to make the connection. I changed the value this morning as the 1000 is the default value set. I had not changed any of those values before.