I stay away from Vaseline, I find it to thick and it is too hard to clean off afterwards.
As far as its use with silicone, I am 98% sure it would be fine. "Natural" oil based lubes are suitable for silicone, think of silicone bake-ware use for cooking. Vaseline is a petroleum base, so that is why I am not 100% sure.
That being said, I am currently testing this kind of thing. Have done my silicone lubes and oil based (Natural) lube testing, my next test will be with petroleum based oil lube. I will be sure to let you, and everyone else know my results in an upcoming Workshop right here on the forums.
If you can not wait that long, try a small bit on the base of the toy. Let it sit there for an hour and clean off.