LSA disappeared

Hi. I got rid of quagga on one of my largest UNIX router, now the log is filling with 'LSA disappeared' messages. Not that it's a huge problem, but how do I get rid of them ? This doesn't look like a network problem or protocol misconfiguration, for example, when an pptp link goes down on a neiboring bird router, I got 'LSA disappeared' about this pptp link on this one. In the same time having log syslog { warning }; looks pretty enough for me. or does this message mean that it's some sort of problem ? Thanks. Eugene.