[Antelope] differening dbsubset results

[N. Seth Carpenter]

Hi, I am using antelope v4.10 on Mac. and am getting different results 
with a dbsubset command when I use it on command line vs. when I use it 
in matlab. 
On command line:
% dbsubset tmp.wfdisc "time >= 1086443800 && time <= 1086447410" | 
dbquery - dbRECORD_COUNT
69

In matlab:
 >> db_wf = dbopen( 'tmp','r' );
 >> db_wf = dblookup_table( 
db_wf,'wfdisc');                                                         
 >> db_wf = dbsubset( db_wf,['time >= ' num2str( 1086443800 ) ' && time 
<= ' num2str( 1086447410 )]);
 >> dbquery( db_wf,'dbRECORD_COUNT' 
)                                                                

ans =

     0

Can someone tell me what I am doing wrong or why I might expect these 
different results?

Thanks,
Seth