You have an extra space between .* and recvd, using \s it reads .*\s\srecvd. You should use \s for spaces to avoid subtle errors like this.
Also including /xms; is good as then you can add comments it forces you to use \s

my $line
    = "Fri May 29 18:29:57.357 2009 Morocco Standard Time INFO: pid 32
+16 tid 1724: 170: 132192: apricocot Native Server: recvd AA_BIN_MSG_V
+ER_CHG";
my $MATCH_TIMESTAMP = qr{
     \A
     ( .*? )  # Capture time-stamp
     \s
     INFO:   
     .*?
     recvd \s AA_BIN_MSG_VER_CHG    
    }xms;

if ( $line =~ $MATCH_TIMESTAMP ) {
    # Made timestamp lexical, you might not want that.
    print my $timestamp = $1;
}
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J,