regex subexpressions broken

[odi]

Configuration Information [Automatically generated, do not change]:
Machine: i686
OS: linux-gnu
Compiler: i686-pc-linux-gnu-gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i686' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL 
-DHAVE_CONFIG_H   -I.  -I. -I./include -I./lib   -march=athlon-tbird -O3 
-fomit-frame-pointer -pipe
uname output: Linux gollum 2.6.18-gentoo-r4 #1 PREEMPT Sat Dec 9 14:19:35 CET 
2006 i686 AMD Athlon(tm) processor AuthenticAMD GNU/Linux
Machine Type: i686-pc-linux-gnu

Bash Version: 3.2
Patch Level: 15
Release Status: release

Description:
[[ "a b c" =~ "a (.) c" ]]
echo ${BASH_REMATCH[1]}

Does not return a result any more. It used to work.
Is that a Gentoo specific problem? Gentoo applies some patches I guess.

Regards

Ortwin