You are perfectly fine and have nothing at all to worry about. You should rest peacefully with your current credit situation!
Like Jville said, might want to prepare a letter. Otherwise, you have nothing to worry about.
I'm in a similar situation -- selling, then building new, and my past is more checkered than yours. I was pre-qual'd too, and not going to sweat it.
LO's know a boat-load about UW because they usually earn a commission based on their approvals!
I was pre-qual'd with a 14 month clean track record... you at 36+ might as well start shopping for welcome mats!