i have heard the general rule of keeping different types of toys seperate due to this sort of thing though silicone toys are generally thought of to be free of this problem was it a full proper silicone toy or one that was the sensafirm silicone or another hybrid polymer silicone, as its only the true silicone (platinum cure and the like) ones that are said to be free of the problem

if it was a true silicone one possibly residue from a lube used on the silicone toy?

beyond that not sure

mrs woly and myself recently just bought some more toys and i've actually kept some of the specially shaped packaging to keep them in to help keep them seperate, in general we dont even let toys of the same type touch just in case

Those Falcon toys, come with a velvety bag w/a drawstring, sounds great, right? but the toy will draw the black  from the velvet & give your toy some funky cow spots.....I just keep 'em in gallon ziplock bags...the toys are too long to seal in the bag but, it gives enough cover to keep them apart, since I started using the ziplocks...no problems other than it takes a longer to put everything away..oh, & always keep the painted label on the bag on the outside(the silicone toys will melt that paint/label), other than that they work great
Also, fyi, not all bags are created equal! I tried just some other longer bags that I had from other things (packaging) & even bread bags...don't do it!...they obviously have a different makeup & will even discolor your toys