Interesting; this is new to me and I've never encountered it. Perhaps native to regional ATP programs, then. It used to be that one was expected to show up to the table with one's ATP in hand; the advent of the ATP courses in the wake of Buffalo perhaps, but that wasn't previously the case and I've never seen one, or met anyone that had such a restriction. Fair enough then: apparently it is possible to get a circling limitation on one's pilot certificate.
This does not change the fact that the original poster was issued a type rating without a circle limitation. The original poster then upgraded his pilot certification to the ATP level. The type rating must remain, without further checking, and without the addition of a circle limitation. Upgrading to the ATP does not, and cannot, introduce a circle limitation to the type rating that did not have such a limitation when held at a lower level of pilot certification.
A type rating that lacks a circle limitation, when held by a commercial pilot certificate holder, does not receive a circle limitation when the commercial pilot certificate holder upgrades his pilot certificate to ATP privileges.