Quoted from mjannusch:
I just noticed last night that there are hairline cracks in the coloration in the return lane covers. Anyone else seeing this? I didn't notice it on any of the other plastics, but these you see all the time... I haven't touched these at all, so it isn't from me overtightening the nuts or something screwy like that.
I would send a ticket to CGC and have them send out replacement plastics for those.