I would use a silicone spray instead.
WD40, although great stuff in the right application, is petroleum based and any over-spray will attract dirt even more than silicone.
It also will more rapidly degrade rubber where silicone will help protect it.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)