I can only relay my own experience, but based on it, I wouldn't worry. There was a rather contentious thread a number of months ago without any real conclusion. You can do a search of this forum if you desire.
I believe that technically there are aptasia on the TBS rock, though the term aptasia is a genus name and not a single species. The type of aptasia that puts people in a panic and spreads like weeds seems to come from the pacific. The type of aptasia (or anemone that looks like it) that shows up on the TBS rock doesn't seem to spread with any vigor.
When I recieved my first shipment, I had 3 very small anemone that looked very similar though not quite like the aptasia running amoak in the LFS's rock tank. Two have disappeared over time and the third has enlarged by maybe 1/2 in six months.
With the second shipment, one rock had a half-dozen anemone that looked much more like the "bad" aptasia. That had me concerned. However, whether it was the pair of peppermint shrimp (still doing great) or other factors, they slowly disappeared over the course of about 2 months. I never saw the shrimp picking at any of them but who knows what happens after lights out? HTH