Nothing unusual going on in the MIA area, and weather looks normal so I would imagine a tech issue.

denCSA - sorry for your long delay but it doesn't happen that often and every airline (including your beloved AA) experiences technical issues. Far better to fix the problem on the ground than at 35,000 ft.@:-)

In all the years I've been doing this route I've only once had a delay - of 2 hours due to cargo loading problems.