There is a Jedediah Gray listed in Census year 1790 (which would obviously make him about 40 around that time) for Worcester County, Virginia. 2 males 16 years old or older, 1 male under 16, and 2 females (also listed 4 slaves). That is all the information provided. I will edit my answer as/if I find any additional information.
(edit) There is a Jediah Gray in a volume labeled "1783 Tax Assessment Maryland".
The entry is as follows:
Jediah Gray. Grays Lott, pt, 130 acres. WO Buckingham and Worcester p. 5. MSA S1161-11-7. 1/4/5/54
(edit) Another possibility:
There is a reference in the AGBI (American Genealogical-Biographical Index) For a Jedediah Gray, born 1750 in Maryland - Volume 66, Page 364.
Reference: Heads of fams. At the first U.S. census. Md. By U.S. Bureau of the Census. Washington, 1907. (189p.):127