Counting runs during play
According to this site Yes it is a run.

Example: Cards are played in this order: 9, 6, 8, 7. The dealer pegs 2 for fifteen when he plays the six and pegs 4 for run when he plays the seven (the 6, 7, 8, 9 sequence). The cards were not played in sequential order, but they form a true run with no foreign card.

I have seen written rules by Hoyle where they are required to be played in order, but every single web site I looked at allow for them to be out of order as long as they aren't interrupted with non-run cards.