Note 6 - Stock-based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Mar. 30, 2019	Sep. 29, 2018
Options outstanding, balance (in shares)	264
Weighted average exercise price per share, (in dollars per share)	$ 29.25
Options outstanding, granted (in shares)	58
Weighted average exercise price per share, granted (in dollars per share)	$ 21.57
Options outstanding, exercised (in shares)	(5)
Weighted average exercise price per share, exercised (in dollars per share)	$ 23.95
Exercised	$ 21
Options outstanding, balance (in shares)	317	264
Weighted average exercise price per share (in dollars per share)	$ 27.93	$ 29.25
Contractual term - weighted average, balance (Year)	7 years 302 days
Aggregate intrinsic value, balance	$ 205
Options outstanding, vested and anticipated to vest in future (in shares)	313
Weighted average exercise price per share, vested and anticipated to vest in future (in dollars per share)	$ 27.91
Contractual term - weighted average, vested and anticipated to vest in future (Year)	7 years 295 days
Aggregate intrinsic value, vested and anticipated to vest in future	$ 205
Options outstanding, exercisable (in shares)	145
Weighted average exercise price per share, exercisable (in dollars per share)	$ 26.05
Contractual term - weighted average, exercisable (Year)	6 years 138 days
Aggregate intrinsic value, exercisable	$ 205
Minimum [Member]
Exercise price per share, balance, lower (in dollars per share)	$ 10.23	10.23
Exercise price per share, granted, lower (in dollars per share)	21.57
Exercise price per share, exercised, lower (in dollars per share)	18.05
Maximum [Member]
Exercise price per share, balance, upper (in dollars per share)	41.85	$ 41.85
Exercise price per share, granted, upper (in dollars per share)	21.57
Exercise price per share, exercised, upper (in dollars per share)	$ 26.75