Why Did Us 1627 Cancel Yesterday?

Last night, I was booked on US 1627 (MidAtlantic), ATL-PIT at 7:45. The inbound flight was late due to maintenance. In ATL, the flight ended up cancelling, again due to maintenance. It was aircraft N809MD. I was just wondering if anyone knew why the flight cancelled?

The US agents in ATL did a terrific job, though. With the inbound flight delayed, they rebooked some people onto the 7:55 CLT flight. When it became evident the flight would be cancelled, the US agents got the PIT-bound pax seats on DL. There were a few of us connecting in PIT to PHL. US put us up in the Westin, gave a meal voucher, and confirmed us on the first ATL-PHL this morning. I was really very impressed with how the agents handled the situation. :up:

I had one other question, too, if someone can help me out. I flew on US 2951 (Mesa) yesterday, the 10:20 CLT-ATL. I was wondering if anyone could tell me the registration number of the CRJ that operated the flight. I couldn't see it from the terminal, but I could see that the letters on the nosegear door were YJZ.
 
It says it cancelled due to A/C maintenance A/C 808 and EMB 170

Mesa flight from CLT-ATL only shows Mesa's own code for the A/C not the actual A/C registration it was YJZ
 
We are supposed to have 1 E70 a day flying in from PIT and back again.90% of the time the flight is either delayed 2 or more hours or cancelled all due to maint. :rant: