Error lines in dnews.log

[Margo Engel]

Hello

Somtimes I can find such rows in my dnews.log

13 06:34:50.404 0:error: Big gap in group, catching up alt.autos.audi
...
13 06:50:40.951 0:error: Big gap in group, catching up rec.arts.dance


Is it a serious error and that does it mean?

Best Regards,
Margo Engel