If you're not using silicone lube there are a few things to keep in mind (silicone lube does strange things with silicone sometimes - worst case scenario is that it bonds with the toy making a gummy mess of the surface, but sometimes it just disappears or makes a temporary welt).

Silicone is sometimes a little "grabbier," especially when it's smooth, soft silicone. This could explain the "tackiness", especially if the tackiness is consistent (doesn't change with the lube).

The other thing is that silicone toys often don't offer much grab to the lube - it just beads up and gets wiped off. This is especially a problem with toys used anally, since the anus tends to have a "squeegee" effect. Thicker lubes tend to stay better, and silicone lubes (that are silicone safe - see the Tantus website link for a good article) as well as oil-based lubes tend to "stick" better to silicone toys.

If the toy is noticeably different than your other stuff from Tantus you may want to ask them about it. Silicone can be picky sometimes, and most places in the US are going through a season change right now so the change in temp and humidity may have affected some things.

Silicone is naturally a little tacky, at least all the shiny/smooth ones I have are, but Tantus stuff is usually really hard and unless you have an O2 product it should be the same hardness as other Tantus stuff. If you have the small silk maybe its just because the toy is thinner?

In any case, if it is a lot different than your other Tantus toys and you know you or anyone else hasnt used silicone lube on it by accident, you should ask them. I am pretty sure they have a warranty.