I have been accused on occasion of being this way.

stolid (stol·id): / STOL id | STAHL id /
adjective

(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.