Either Lydia's deathdate is wrong or Hannah's marriage date is wrong, and my bet would be on the latter because I would trust Loomis (1909) as a source over a patron submission to the IGI (see sources below).

1.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

Truman GALUSHA Spouse: Lydia LOOMIS Marriage: 17 Sep 1809, Shaftbury, Bennington, Vermont Source: patron submission

Truman GALUSHA Spouse: Hannah CHITTENDEN Marriage: 1819 <shaftsbury>, Bennington, Vermont Source: [patron submission]

When a marriage date includes only the year and has no day or month, you can be pretty sure the marriage date is a guess or, at best, an estimate.

2.  Census Index:  U.S. Selected Counties, 1810 (Broderbund CD-313):

1810

Galusha, Truman

VT

Bennington Co.

Shaftsbury

p. 129

There are several GALUSHAs in Bennington Co., but he is the only Truman GALUSHA on the CD.

3.  Census Index:  U.S. Selected Counties, 1820 (Broderbund CD-314):

1820

Galusha, Truman

VT

Bennington Co.

Shaftsbury

p. 106

There are many GALUSHAs in Bennington Co., but he is the only Truman GALUSHA on the CD.

4.  Census Index:  U.S. Selected Counties, 1830 (Broderbund CD-315):

1830

Galuska, Truman

VT

Chittenden Co.

Jericho

p. 277

The only other GALUSHA in the county is his uncle, Ezra GALUSHA.  He is the only Truman GALUSHA on the CD. 

5.  Census Index:  U.S. Selected Counties, 1840 (Broderbund CD-316):

1840

Galusha, Truman

VT

Chittenden Co.

Jerico

p. 16

The only other GALUSHA in the county is his son, "T.C. GALUSHA"

6.  1850 Census Index/Microfilm (online at GenealogyLibrary.com):  Jericho, Chittenden Co., VT, p. 24B, 54/54, enumerated 9 Sep 1850 (extracted by Diana Gale Matthiesen):

Trueman Galusha	63	M	Farmer	10,000	Vermont
Russell H  "	34	M	"	2,700	"
Lydia J    "	29	F			"
Catherine Haven	19	F			Ireland

Listed between presumed son, Rollin? M. GALUSHA (age 30, b. VT, wife Julia), and Hannah's uncle, Amos FASSETT (age 70, b. VT, wife Sally), and ten households from son, Truman C. GALUSHA.  They are the only GALUSHAs in the county. 

7.  Elisha Scott Loomis, ed.  1909.  Descendants of Joseph Loomis in America and His Antecedents in the Old World, the Original Published by Elias Loomis LL.D., 1875.  Self-published, Berea, OH (available as a fascimile reprint from New England Historic Genealogical Society, Boston, MA; online at GenealogyLibrary.com).  See longer excerpt. 

p. 223	1082.  RUSSELL LOOMIS, b. Colchester, Conn., Sept. 1, 1763; m. 2nd? June 17, 1790, Lydia, b. May 16, 1770, d. Apr. 3, 1835, ae. 65, dau. of Amos and Peace (Clark) Huntington.  He d. Feb. 22, 1842, Shaftsbury, Vt. 7 ch'n. See Huntington Gen., p. 150. 2699.  LYDIA, b. Mch. 18, 1791; m. 1809. Truman Galusha. She d. 1825. Jericho, Vt...
p. 714 (index)	1699. Galusha, Truman | Jericho, Vt.

8.  Anon.  1915.  The Huntington Family in America: a Genealogical Memoir of the Known Descendants of Simon Huntington from 1633 to 1915.  Huntington Family Assn., Hartford, CT (online at GenealogyLibrary.com).  See excerpt. 

9.  Alvan Talcott. 1984.  Families of Early Guilford, Connecticut.  Genealogical Publ Co., Baltimore, MD (Broderbund CD-515).  In Vol. 1, on p. 180:

49. Noah Chittenden, son of Gov. Thomas and Elizabeth (Meigs), married Sally Fasset.     Children...         Anna, mar Truman Galusha

10.  LDS.  Family Search: Internet Genealogy Service:  AF - Ancestral File (online at FamilySearch.org).

11.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).