Note 3 - Summary of Significant Accounting Policies - Stock Option Activity (Details) - $ / shares	3 Months Ended				9 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Dec. 30, 2016	Jun. 30, 2018	Jul. 01, 2017
Outstanding, unvested (in shares)	43,100	34,200	34,200		34,200
Outstanding, vested (in shares)	185,737	212,081	212,081		212,081
Outstanding (in shares)	228,837	246,281	246,281		246,281
Outstanding, weighted average exercise price (in dollars per share)	$ 8.48	$ 8.35	$ 8.36		$ 8.36
Outstanding, weighted average contractual life (Year)	3 years 335 days	4 years 62 days	3 years 262 days	3 years 346 days
Grants, unvested (in shares)		14,500			14,500	14,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		14,500			14,500	14,000
Grants, weighted average exercise price (in dollars per share)		$ 7.25
Cancellations/forfeitures (in shares)		(7,844)
Grants, vested (in shares)
Vested, unvested (in shares)	(3,100)	(5,600)
Vested, vested (in shares)	3,100	5,600
Vested, weighted average exercise price (in dollars per share)	$ 4.25	$ 2.70
Exercises, vested (in shares)		(24,100)
Exercises (in shares)		(24,100)
Exercises, weighted average exercise price (in dollars per share)		$ 6.12
Cancellations/forfeitures, vested (in shares)		(7,844)
Cancellations/forfeitures, weighted average exercise price (in dollars per share)		$ 9.68
Outstanding, unvested (in shares)	40,000	43,100	34,200		40,000
Outstanding, vested (in shares)	188,837	185,737	212,081		188,837
Outstanding (in shares)	228,837	228,837	246,281		228,837
Outstanding, weighted average exercise price (in dollars per share)	$ 8.48	$ 8.48	$ 8.35		$ 8.48