TM and B/U delayed

I just noticed that my TM backup has a message that says "Backup Delayed" with the last B/U over two (2) days ago. I checked the TM preferences and they are normal. I can't find anything in the logs that helps.

So I told TM to B/U now and it seems to be back to normal.

Any guess as to what may have happened?

Thanks in advance,

Kim