One note is that it doesn't happen immediately after starting. IE, the first few stops it won't happen, but once it does, it will happen again at each long stop for the rest of the drive (even after 2-3 hours of highway driving).
I am getting the sub-frame bolts replaced next week and will have the dealership investigate the following things based upon feedback in this thread:
I need to keep this limited as this issue is a black box to the shop, even if they can reproduce it in a tech test drive and I will be charged for diagnosis time.
And just to note again, I have no mods except a disconnected and plugged flapper vacuum tube and AFE panel lifetime air filter. All maintenance should be up to date AFAIK.