Note 2 - Summary of Significant Accounting Policies - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Outstanding, unvested (in shares)	44,700	34,200
Outstanding, vested (in shares)	182,437	212,081
Outstanding (in shares)	227,137	246,281
Outstanding, weighted average exercise price (in dollars per share)	$ 8.50	$ 8.36
Outstanding, weighted average contractual life (Year)	3 years 361 days	3 years 277 days	3 years 346 days
Grants, unvested (in shares)	34,500	20,500
Grants, vested (in shares)	6,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	40,500	20,500
Grants, weighted average exercise price (in dollars per share)	$ 3.58	$ 6.22
Vested, unvested (in shares)	(16,000)	(10,000)
Vested, vested (in shares)	16,000	10,000
Vested, weighted average exercise price (in dollars per share)	$ 3.96	$ 3.25
Exercises, vested (in shares)		(31,800)
Exercises (in shares)	0	(31,800)
Exercises, weighted average exercise price (in dollars per share)		$ 5.60
Cancellations/forfeitures, unvested (in shares)	(3,800)
Cancellations/forfeitures, vested (in shares)	32,500	(7,844)
Cancellations/forfeitures (in shares)	(36,300)	(7,844)
Cancellations/forfeitures, weighted average exercise price (in dollars per share)	$ 6.24	$ 9.68
Grants (in shares)	40,500	20,500
Cancellations/forfeitures, vested (in shares)	(32,500)	7,844
Outstanding, unvested (in shares)	59,400	44,700	34,200
Outstanding, vested (in shares)	171,937	182,437	212,081
Outstanding (in shares)	231,337	227,137	246,281
Outstanding, weighted average exercise price (in dollars per share)	$ 8	$ 8.50	$ 8.36