I saw on mine that at at each high point (the grey plastic ) was flat. That the plastic had snapped at each point. If that is the" friction weld " you speak of , then yea. But I am not familiar with the exact name of parts and doesn't sound right.
The other pieces of grey plastic where still attached to the underneath of the spoiler, would have been attached to each high spot along the back. So it's the cheap grey plastic (I called clips ) pardon for not naming it right ,snapped.
PBM GT W/SPORT PACK
Pat G tune
EXHAUST: BADLANDZ CUT OUTS W/ X PIPE AND RESONATOR DELETE
KOOKS 1 7/8 mids and HFC's (coated)
PONTIAC EMBLEMS REMOVED. HOLDEN TRUNK LOGO ADDED.