There seems to be a rare "bug"/situation in lame that sometimes corrupts the lame tag. Here's what sometimes happens on one song when ripping with EAC and encoding with lame 3.92 with --alt-preset standard:

* EncSpot can't read the lame tag, identifies the header info as Unknown
* both Winamp 2 and 3 show the bugged mp3 file length to be MUCH longer in the playlist than what it really is
* but the ID3 tags, both v1 and v2, are fine

Any info on this "bug" and when it happens?

It might simply be because you have an id3v2 tag at the beginning

Sorry, I don't know what you mean. If all the songs in an album have ID3V2 tags at the beginning but this happens only to one song in the album how can the ID3V2 tag be involved?