I have been accused on occasion of being this way.
stolid (stol·id): / STOL id | STAHL id /
(1) impassive; unemotional; not easily stirred or moved; expressing or possessing little or no sensibility
[From Latin stolidus meaning “dull, stupid (, or inert).”]
Usage: I felt grave concern for the child’s stolid reaction to hearing of his mother’s accident.