Loop in the cross connect if nothing is connected to the port?

Hi all,

We came across some strage cases on our DC Cisco devices when nothing was connected to the port, but the interface was left in admin up state. There were signs of network loop, we got mac-move alerts on switches, on router's the routing protocol got back it's own system id. These did not happen at once, but from time to time we face some strange behaviour. And it disappeared without any intervention.

Do you think that the DC provider is able to loop the lines if it is not connected to anything? Have you met anything similar?

I did not hear anything from the DC yet that could cause this and to be frank it is hard to put the whole thing in words and find the right question to ask.