this is why. the interval starts at 150,a nd that is when teh query is sent. on the stray, we hit it in 151:
2011-10-31 10:35:49.794331 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 140/140/93) [18,21] r=1 lcod 0'0 inactive] enter Reset
2011-10-31 10:35:49.794350 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 140/140/93) [18,21] r=1 lcod 0'0 inactive] state<Reset>: Reset advmap
2011-10-31 10:35:49.794381 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 140/140/93) [18,21] r=1 lcod 0'0 inactive] state<Reset>: up or acting affected, calling start_peering_interval again
2011-10-31 10:35:49.794405 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] noting past interval(140-149 [18,21]/[18,21] maybe_went_rw)
2011-10-31 10:35:49.794426 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] up [18,21] -> [18,21,4], acting [18,21] -> [18,21,4], role 1 -> 1
2011-10-31 10:35:49.794441 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] cancel_generate_backlog
2011-10-31 10:35:49.794457 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] on_change
2011-10-31 10:35:49.794472 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] remove_watchers
2011-10-31 10:35:49.794491 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] exit NotTrimming
2011-10-31 10:35:49.794510 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] enter NotTrimming
2011-10-31 10:35:49.794529 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] cancel_recovery
2011-10-31 10:35:49.794546 7fe305f59700 osd.21 150 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] clear_recovery_state
2011-10-31 10:35:49.921000 7fe305f59700 osd.21 151 Scanning pg pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive]
2011-10-31 10:35:49.921022 7fe305f59700 osd.21 151 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] handle_advance_map [18,21,4]/[18,21,4]
2011-10-31 10:35:49.921044 7fe305f59700 osd.21 151 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] state<Reset>: Reset advmap
2011-10-31 10:35:50.247961 7fe305f59700 osd.21 151 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] handle_activate_map
2011-10-31 10:35:50.247981 7fe305f59700 osd.21 151 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] exit Reset 0.453649 2 0.000000
2011-10-31 10:35:50.248000 7fe305f59700 osd.21 151 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] enter Started
2011-10-31 10:35:50.248019 7fe305f59700 osd.21 151 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] enter Start
2011-10-31 10:35:50.248056 7fe305f59700 osd.21 151 pg[7.5( v 87'98 (87'96,87'98] n=34 ec=41 les/c 111/113 150/150/93) [18,21,4] r=1 lcod 0'0 inactive] state<Start>: transitioning to Stray