Thanks all.
I do wash my DD in the garage in the winter; so maybe the salty water is getting in the gaps and with warmer weather expanding back up and through the same spaces?
I will wipe them down with some cleaner.
Glad I have plastic underneath my summer car. :)
Has anyone used this stuff on their used RD tiles??
I cleaned mine but they still look kinda dull and am hoping this stuff will restore the shine with minimal labor.
Thanks