Note 5 - Income Taxes - Deferred Income Taxes (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Deferred tax assets:
Accrued expenses	$ 406	$ 287
Deferred stock compensation	321	469
Bad debt and inventory reserves	29	24
Total deferred tax assets	756	780
Deferred tax liabilities:
Property and equipment	(2,037)	(1,750)
Total net deferred tax liabilities	$ (1,281)	$ (970)